Video of an explosion in Kyiv Oblast presumably caused by Russian cruise missiles.

KYIV/LVIV, Ukraine, April 15 (Reuters) - Powerful explosions were heard in Kyiv on Friday and fighting raged in the east after Ukraine claimed responsibility for the sinking of the Russian navy's Black Sea flagship in what would be one of the heaviest blows of the war.

The explosions appeared to be among the most significant in Ukraine's capital region since Russian troops pulled back from the area earlier this month in preparation for battles in the south and east.

Ukraine said it hit the Moskva missile cruiser with a Neptune anti-ship missile. The Soviet-era ship sank on Thursday as it was being towed to port following a fire and explosions, Russia's defence ministry said. read more

Over 500 crew were evacuated, the ministry said, without acknowledging an attack.

The ship's loss comes as Russia's navy continues its bombardment of Ukrainian cities on the Black Sea nearly 50 days after it invaded the country to root out what it calls far-right nationalists.

Ukrainian President Volodymyr Zelenskiy paid homage to all "those who halted the progress of the endless convoys of Russian military equipment ... Those who showed that Russian ships can go ... down to the bottom."

There were no immediate reports of damage following the explosions reported in Kyiv, Kherson in the south, the eastern city of Kharkiv and the town of Ivano-Frankivsk in the west.