March 24 (Reuters) - Ukraine's leader called for solidarity on Thursday, a month after Russia's invasion began, warning he would see who sells out at summits in Europe, where plans to bolster sanctions and NATO are afoot but restrictions on energy could prove divisive.

U.S. President Joe Biden has arrived in Brussels for meetings of the alliance, G7 and EU over a conflict that began on Feb. 24 and has caused more than 3.6 million refugees to flee the country.

ON THE GROUND * NATO Secretary-General Jens Stoltenberg said the alliance would boost its forces in Eastern Europe by deploying four new battle groups in Bulgaria, Hungary, Romania, Slovakia. * The United States said it has assessed that members of Russia's forces have committed war crimes in Ukraine, U.S. Secretary of State Antony Blinken said.

None of the following reports could immediately be verified: * Kyiv Mayor Vitali Klitschko told reporters on Wednesday that 264 civilians in the city had been killed by Russian attacks. He later said one person was killed and two wounded on Wednesday when shells hit a shopping centre parking lot. Russia has denied targeting civilians. * Russia said its forces used long-range weapons fired from the sea to hit a Ukrainian arms depot outside the northwestern city of Rivne and two Tochka-U missile launchers in an industrial zone in the outskirts of Kyiv.

REPERCUSSIONS * The U.S. Embassy in Moscow on Wednesday received a list of its diplomats declared "persona non grata", a State Department spokesperson said, in what Russian media said was a response to a U.S. move ousting Russian staff at the United Nations. * Russia plans to switch its gas sales to "unfriendly" countries to roubles, President Putin said, responding to a freeze on Russia's assets by foreign nations. CIVILIANS * A senior Ukrainian official said 4,554 people were evacuated from cities through humanitarian corridors on Wednesday. * More than 145,000 babies are in urgent need of nutrition support in Ukraine, UNICEF said.

QUOTES * "Come from your offices, your homes, your schools and universities, come in the name of peace, come with Ukrainian symbols to support Ukraine, to support freedom, to support life," Zelenskiy said in his appeal for a worldwide March 24 demonstration. * "We, the French and Europeans, will do everything to stop this war without entering it," said French President Macron. (Compiled by Philippa Fletcher, Alex Richardson, Grant McCool and Michael Perry. Edited by Gerry Doyle)