Russia has warned of plans to intensify missile attacks on Kyiv a day after losing the Black Sea fleet flagship the Moskva. 

The country's defence ministry issued the threat of increased attacks amid accusations that Ukraine had wounded seven people with alleged airstrikes on Bryansk.

Ukrainian officials have not confirmed striking targets in Russia, and the reports by Russian authorities could not be independently verified.

Russia's offensive on the Ukrainian capital had diminished in recent days as their forces focused on a concentrated assault in the eastern regions.  

A renewed bombardment could return the capital’s residents to sheltering in subway stations and the steady wail of air raid sirens.

The warning comes after Ukrainian officials claimed to have struck a key Russian warship with missiles on Thursday. 

The guided-missile cruiser Moskva, named after the Russian capital, sank while being towed to port on Thursday after suffering heavy damage under circumstances that remained in dispute.

Moscow acknowledged a fire on board but not any attack. US and other Western officials could not confirm what caused the blaze.

READ MORE: Russian flagship Moskva sinks after alleged missile strike

If Ukrainian forces took out the vessel, the Moskva probably represents the largest warship to be sunk in combat since the Falklands War.

A British submarine torpedoed an Argentine navy cruiser called the General Belgrano during the 1982 conflict, killing more than 300 sailors on board.

The Russian warship’s loss in an invasion already widely seen as a historic blunder was also a symbolic defeat for Moscow as its troops regroup for an offensive in eastern Ukraine after retreating from the Kyiv region and much of the north.

In his nightly address on Thursday, Ukrainian President Volodymyr Zelensky said the people of his country should be proud of having survived 50 days under attack when the Russian invaders “gave us a maximum of five”.