Russia said on Saturday it had "no intention" of invading eastern Ukraine, responding to Western warnings over a military buildup on the border following Moscow's annexation of the Crimean peninsula.
The comments by Foreign Minister Sergei Lavrov were followed by news that he would meet U.S. Secretary of State John Kerry in Paris on Sunday, as both sides moved to ease tensions in the worst East-West standoff since the Cold War.
Speaking on Russian television, Lavrov reinforced a message from President Vladimir Putin that Russia would settle - at least for now - for control over Crimea despite massing thousands of troops near Ukraine's eastern border.
(Read more: Putin calls Obama to discuss US proposal on Ukraine: White House)
"We have absolutely no intention of - or interest in - crossing Ukraine's borders," Lavrov said.
Putin called U.S. President Barack Obama on Friday to discuss a U.S. diplomatic proposal, with the West alarmed at the threat to Ukraine's eastern flank from what U.S. officials say may be more than 40,000 Russian soldiers.
Lavrov added, however, that Russia was ready to protect the rights of Russian speakers, referring to what Moscow sees as threats to the lives of compatriots in eastern Ukraine since Moscow-backed Viktor Yanukovich was deposed as president in February.
The West imposed sanctions on Russia, including visa bans for some of Putin's inner circle, after Moscow annexed Crimea this month following a referendum on union of the Russian-majority region with the Russian Federation which the West said was illegal.
The West has threatened tougher sanctions targeting Russia's stuttering economy if Moscow sends more troops to Ukraine.
NATO Secretary General Anders Fogh Rasmussen, in an interview with Germany's Focus magazine published on Saturday, said the alliance was "extremely worried".
"We view it as a concrete threat to Ukraine and see the potential for further interventions," said Rasmussen, who is due to leave the post in October.
"I fear that it is not yet enough for him (Putin). I am worried that we are not dealing with rational thinking as much as with emotions, the yearning to rebuild Russia's old sphere of influence in its immediate neighborhood."
U.S. State Department spokeswoman Jen Psaki said Lavrov and Kerry would meet on Sunday in the French capital. They spoke by phone on Saturday, following up on the Putin-Obama call on Friday.
The White House said Obama had told Putin that Russia must pull back its troops and not move deeper into the ex-Soviet republic. The Kremlin said Putin had suggested "examining possible steps the global community can take to help stabilize the situation.
Ukraine remains deeply divided over protests that led to Yanukovich's ousting and many eastern Russian-speaking regions are skeptical about the policies of the new pro-Western government in Kiev.
Yanukovich called on Friday for each of the country's regions to hold a referendum on their status within Ukraine, instead of the presidential election planned for May 25.
That election is shaping up as a context between former prime minister Yulia Tymoshenko and billionaire confectionary oligarch Petro Poroshenko, after boxer-turned-politician Vitaly Klitschko withdrew on Saturday.
Lavrov called for "deep constitutional reform" in Ukraine, a sprawling country of 46 million people divided between those who see their future in closer ties with Europe and mainly Russian speakers in the east who look to former Soviet master Russia.
"Frankly speaking, we don't see any other way for the steady development of the Ukrainian state apart from as a federation," Lavrov said.
Each region, he said, would have jurisdiction over its economy, finances, culture, language, education and "external economic and cultural connections with neighboring countries or regions".
"Given the proportion of native Russians (in Ukraine) we propose this and we are sure there is no other way," Lavrov said, and Russia had briefed Western powers and others on the proposal.
There was also a bid for regional devolution within Crimea. Its Tatar community, an indigenous minority who were persecuted under Soviet rule and largely boycotted last month's referendum on joining Russia, want autonomy on the Black Sea peninsula, the Tatar leader said on Saturday.
- By Reuters