* Washington, Brussels say referendums illegal
* Russia stops short of recognising independence
* Biggest self-proclaimed independent states in Europe since 1990s
(Adds EU sanctions list)
DONETSK/SLAVIANSK, Ukraine, May 12 (Reuters) - Pro-Moscow rebel leaders in eastern Ukraine called on Monday for their region to become part of Russia, the day after staging a referendum on self-rule, although Moscow stopped short of endorsing their bid for annexation.
Announcing the result of the vote in one of the two provinces where it was held, a leader of the "People's Republic of Donetsk", Denis Pushilin, said it was now an independent state and would appeal to join the Russian Federation.
"The people of Donetsk have always been part of the Russian world. For us, the history of Russia is our history," he said.
"Based on the will of the people and on the restoration of historic justice, we ask the Russian Federation to consider the absorption of the Donetsk People's Republic into the Russian Federation," he told a news conference.
There and in neighbouring Luhansk, some officials said they might now hold a second referendum on joining Russia, like one held in Crimea, a Ukrainian region Moscow seized and annexed in March after protesters ousted Ukraine's pro-Russian president.
Donetsk and Luhansk together are home to 6.5 million people and represent around a third of Ukraine's industrial output. Their declarations create the biggest new self-proclaimed independent states in Europe since Yugoslavia, Czechoslovakia and the Soviet Union itself broke up more than 20 years ago.
Donetsk separatists said that more than 80 percent of voters had supported independence. Those in Luhansk said more than 96 percent did.
The government in Kiev and its Western supporters say the exercise was absurd, with no legal basis, insecure polling stations, old voter lists, ballots that could be easily reproduced and self-proclaimed election officials openly promoting secession. They say many residents support a united Ukraine but would have stayed home, both out of fear of rebel gunmen and to avoid lending the vote credibility.
Unlike in Crimea, Moscow has not recognised the two regions as independent from Kiev and has said nothing to suggest it would endorse their absorption into Russia. President Vladimir Putin even called last week for the referendum to be postponed.
But Moscow indicated clearly on Monday that it intends to use the results of the referendums to put more pressure on the government in Kiev to recognise the rebels in the east as a legitimate side in talks.
"We believe that the results of the referendum should be brought to life within the framework of dialogue between Kiev, Donetsk and Luhansk," the Russian Foreign Ministry said.
It accused the Kiev government of a "criminal lack of readiness for dialogue with their own people".
The Russian stance appears calculated to entrench Moscow's allies in control of Ukraine's industrial heartland without taking the sort of overt steps - sending in ground forces or formally recognising the regions' split from Kiev - that might invite tough sanctions from the West.
The mayor of Slaviansk, a small city in the Donetsk region that has become the most heavily fortified rebel redoubt, said Ukrainian troops were now occupiers, and Russian troops should be invited to help defend the area.
"They should go," Vyacheslav Ponomaryov said of Ukrainian forces. "We're going to defend our territory." As for bringing in Russian forces: "I support this. We need Russian troops to provide stability and a peaceful life in the region's future."
The European Union added the names of 13 people and two Crimean firms on Monday to a list of those facing asset freezes and travel bans, measures Moscow has mocked as pointless.
The new names include Putin's first deputy chief of staff, Vyacheslav Volodin, but notably exclude bosses of big Russian companies. Earlier U.S. lists have included the head of Russia's biggest oil company and the co-founder of a big oil trader, but not the firms themselves, which say operations are unaffected.
But both Brussels and Washington have so far eschewed wider "sectoral sanctions" on Russian industry designed to hurt Russia's economy more broadly, despite repeatedly threatening to impose them. The EU does more than 10 times as much trade with Russia as the United States, and big companies have lobbied against sanctions that would hurt their business.
The United States and European Union both said they would not recognise the results of the "illegal" referendum.
"We will not recognise the so-called referendums of yesterday. They are illegal, illegitimate and incredible," Herman Van Rompuy, president of the European Council of EU leaders, told a news conference in the Ukrainian capital.
However, in the latest sign that the West is not ready to impose more serious economic measures, diplomatic sources said France would press ahead with a 1.2 billion-euro ($1.7 billion) contract to sell helicopter carrier ships to Russia because cancelling it would hurt Paris more than Moscow.
Losing control of Donetsk and Luhansk would be a crippling blow for Ukraine, a country of around 45 million people the size of France and facing bankruptcy after half a year of turmoil.
Donetsk and Luhansk yield more than 15 percent of Ukraine's GDP, including around a third of its industrial output from the giant steel smelters and other heavy industry of the Donbass, one of Europe's most productive coal-producing regions.
If they slip out of Kiev's control without being formally absorbed by Moscow, they would become by far the biggest and most economically important of the self-proclaimed independent statelets Russia protects in other parts of the ex-Soviet Union.
Since the early 1990s Russian troops have shielded breakaway statelets in a sliver of Moldova and two parts of Georgia, but all three of those regions combined have barely an eighth of the population of Donetsk and Luhansk.
The International Monetary Fund, which is arranging a bailout of Ukraine's finances, has said it would have to renegotiate if Kiev lost control of the east.
The government in Kiev and Western nations accuse Russia of stirring up unrest in the east following the overthrow of president Viktor Yanukovich in February by protesters demanding closer links with Europe.
Since March, Putin has overturned decades of post-Cold War diplomacy by announcing Russia's right to intervene in Ukraine, taking over Crimea and massing tens of thousands of troops on the frontier. Putin said last week he had withdrawn the troops from the border area, but Washington and NATO said this was not true. They also say Russian special forces are active on the ground, which Moscow denies.
Ukraine's acting President Oleksander Turchinov accused Russia of working to overthrow legitimate state power in Ukraine. He said the Kremlin was trying to disrupt a Ukrainian presidential election later this month.
Eastern Ukraine has been plagued by turmoil as Kiev has staged a largely failed military operation to regain control of towns held by the separatists. Authorities said 49 people have been killed in violence in the region of Donetsk since March 13.
REPUBLIC OF LUHANSK
The rebels have given differing accounts of their precise plans. However, participating in the Ukrainian presidential election on May 25 is clearly ruled out.
"As of today, we are now the Republic of Luhansk, which believes it to be inappropriate and perhaps even stupid to hold a presidential election," Russia's RIA news agency cited a spokesman for rebels in that region as saying.
While some rebels seem content with independence, some have publicly supported pressing for annexation by Russia.
"This land was never Ukraine ... We speak Russian," said Ponomaryov in Slaviansk. Asked about a possible second referendum to join Russia, he said: "There has been no decision, but this referendum showed we are prepared ... We can put on an election or referendum at short notice at barely any cost."
Ukrainian Interior Minister Arsen Avakov said rebels had made a new attempt overnight to seize a television tower on the edge of Slaviansk. Eastern regions of Ukraine receive Russian state television, which has broadcast relentless accounts of a threat from "fascists" in Kiev. Ukraine has struggled to keep its own television stations on the air in the region.
"The information war that they are waging against us in the Donbass is more dangerous than a bullet," he wrote on Facebook.
But there was hint of compromise in the port of Mariupol, scene of fierce fighting between Ukrainian forces and rebels over the last week. Turchinov said police had begun patrols with a volunteer militia set up by Metinvest, a firm mostly owned by Ukraine's wealthiest man, Rinat Akhmetov, who controls much of the industry in Donetsk.
(Additional reporting by Pavel Polityuk in Kiev, Lidia Kelly in Moscow, Adrian Croft and Justyna Pawlak in Brussels, John Irish, Marine Pennetier and Elizabeth Pineau in Paris; Writing by Peter Graff; Editing by Mark Heinrich)