WRAPUP 12-Ukraine to call for heavy arms when top U.S. officials visit Kyiv

(Updates with details on meeting, casualty figures)

* U.S. has not confirmed visits by Blinken, Austin

* West has been sending more powerful arms to Ukraine

* Ukrainians mark Orthodox Easter across Europe

* Ukraine says destruction of churches disrupt celebrations

* Moscow says military sites hit, Kyiv says children killed

By Pavel Polityuk and Natalia Zinets

KYIV, April 24 (Reuters) - Ukraine will ask U.S. Secretary of State Antony Blinken and Defence Secretary Lloyd Austin for more powerful weapons during an expected visit by the officials to Kyiv on Sunday as the Russian invasion enters its third month.

Ukrainian President Volodymyr Zelenskiy said his country would overcome "dark times," in an emotional address at Kyiv's 1,000-year-old Saint Sophia Cathedral to mark Orthodox Easter as fighting in the east overshadowed the religious celebrations.

The trip by Blinken and Austin, announced earlier by Zelenskiy, would be the highest-level visit to Ukraine by U.S. officials since Russian President Vladimir Putin ordered the invasion of the country on Feb. 24.

The White House has not confirmed any visit, and the State Department and Pentagon declined to comment. But Oleksiy Arestovych, an adviser to Zelenskiy, said late on Sunday in a social media video that Blinken and Austin had arrived in Kyiv and were holding talks with the Ukrainian president.

"We are inspired by the resilience of Orthodox Christians in Ukraine in the face of President Putin's brutal war of aggression," Blinken said earlier on Twitter.

Zelenskiy on Twitter thanked U.S. President Joe Biden and the United States for leadership in supporting Ukraine.

After Ukrainian fighters forced a Russian retreat from around Kyiv, Moscow's assault is now focused on the eastern Donbas region and the south of the country. With a semblance of normal life returning to the capital, several countries have reopened embassies in recent days and some residents who fled the fighting returned for Easter.

Moscow, which describes its actions in Ukraine as a "special military operation", denies targeting civilians and rejects what Ukraine says is evidence of atrocities, saying Kyiv staged them to undermine peace talks.

Pope Francis called for an Easter truce: "Stop the attacks in order to help the exhausted population. Stop," he said.

Ukrainian refugees filled churches across central Europe.

"I pray that this horror in Ukraine ends soon and we can return home," said Nataliya Krasnopolskaia, who fled to Prague from Odesa last month, one of the more than 5 million Ukrainians estimated to have escaped the country.