UPDATE 5-Oil falls to 3-week low on Ukraine hopes, stronger dollar after ECB

* Ukraine president-elect works on peace plan with Western leaders

* U.S. crude stockpiles fell 3.4 mln barrels last week - EIA

* ECB announces rate cut, dollar gains

(Adds ECB decision, updates prices)

LONDON, June 5 (Reuters) - Oil fell to a three-week low below $108 a barrel on Thursday as worries about risks to supply caused by violence in Ukraine eased on hopes that talks could resolve the situation.

Oil was also pressured as the dollar gained against the euro after the European Central Bank cut interest rates to record lows and imposed negative rates on its overnight deposits.

Crude, denominated in the U.S. unit, is pressued when the dollar rises as it becomes less affordable to holders of other currencies.

Brent crude futures fell for a fifth session, their longest losing streak since early January, and were down 42 cents at $107.98 a barrel by 1222 GMT. Brent earlier hit $107.86, its lowest since May 9.

Geopolitical tensions pushed up Brent to above $111 a barrel last month, but prices have shed about 3 percent since then.

U.S. crude fell 43 cents to $102.21 a barrel.

Ukraine's President-elect Petro Poroshenko said he may discuss a plan to end violence in eastern Ukraine with Russian leader Vladimir Putin.

Putin will hold face-to-face meetings with German Chancellor Angela Merkel, French President Francois Hollande and British Prime Minister David Cameron at a D-Day anniversary gathering in France later this week.

This helped allay concerns that conflict in Ukraine, a main gas supply route to Europe from Russia, could disrupt oil supplies as well.

"Avenues of communication are open and the talks this weekend mean the market is not as concerned as it was when the Crimea crisis erupted," Christopher Bellew, broker at Jefferies Bache, said.

Investors are eyeing an announcement later on Thursday from the European Central Bank, which might unveil plans to introduce growth-boosting stimulus - a result that could lift oil demand.

Worries about the demand outlook for China, the world's biggest energy consumer, also kept prices in check.

The International Monetary Fund (IMF) cut its 2015 economic growth forecast for China to about 7 percent, but urged authorities to avoid further stimulus measures and concentrate on curtailing financial risks instead.

Brent's premium to West Texas Intermediate (WTI) crude <CL-LCO1=R> on Wednesday fell below $6, its narrowest since April 15, after crude stockpiles in the United States dropped more than expected on lower imports and higher refinery utilisation.

But crude stocks remain near the top of the typical range for this time of year and an overall 8.8-million-barrel rise in total hydrocarbon inventories last week painted a bearish picture, BNP Paribas analysts said in a note.

"The scope for further increases in refinery runs from these levels however appears limited to us in the absence of a marked rise in product exports," the analysts said.

The United States is unlikely to repeat the sharp seasonal decline in crude stocks seen in June-July last year, due to strong domestic production, they said.

The United States will also release employment data on Friday that may reinforce a recovery trend in the world's largest economy.

(Additional reporting by Florence Tan in Singapore; Editing by Dale Hudson and William Hardy)