TOP WRAP 1-On invasion milestone, Ukraine urges solidarity as Western leaders gather

* Zelenskiy urged people to take to the streets in show of support

* U.S. to impose more sanctions on Russia

* Putin says some gas contracts must be paid in roubles

* Blinken says war crimes committed by Russians

By Natalia Zinets, Vitalii Hnidiy and Jarrett Renshaw

LVIV/KHARKIV, Ukraine/ BRUSSELS, March 24 (Reuters) - U kraine's leader called for solidarity on Thursday, a month since Russia's invasion began, warning he would see who sells out at summits in Europe where bolstering sanctions and NATO is planned 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.

Biden's visit could also shine light on a dispute with European allies, some of whom are heavily reliant on Russian oil and gas, over whether to impose further energy sanctions.

The issue has been a "substantial" topic and the subject of "intense back and forth" in recent days, White House national security adviser Jake Sullivan told reporters. The United States has already banned imports of Russian oil.

President Vladimir Putin on Wednesday said Moscow planned to switch gas sales made to "unfriendly" countries to roubles.

As the humanitarian toll from the conflict continues to rise, driving a quarter of Ukraine's population of 44 million from their homes, President Volodymyr Zelenskiy called on people around the world to take to the streets and demand the war end.

"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," he said in a video address.

The United States planned to announce more sanctions on Russian political figures and oligarchs on Thursday, and officials would have more to say on Friday about European energy issues, Sullivan said.

Ahead of his meeting with Biden, 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.

Zelenskiy said on Thursday he expected "serious steps" from Western allies.

He repeated his call for a no-fly zone and complained that the West had not provided Ukraine with planes, modern anti-missile systems, tanks or anti-ship weapons.

"At these three summits we will see who is our friend, who is our partner and who sold us out and betrayed us," he said in a video address released early on Thursday.