Russia vows to complete 'special military operation'

Western weapons and intelligence being supplied to Ukraine will "slow down but won't stop" Russia from completing its "special military operation", Kremlin spokesman Dmitry Peskov said.

Peskov made the remarks as NBC News reported on Thursday that United States' intelligence helped Ukraine sink Russia's Moskva missile cruiser last month, as the Pentagon denied an earlier report which said US intelligence has also allowed Kyiv to kill Russian generals.

Ukrainian forces targeted the Moskva on April 13 after asking the US to help identify and confirm its location in the Black Sea, the broadcaster cited unnamed US officials as saying.

The officials added that Ukraine alone decided to target Russia's Black Sea Fleet flagship using its own anti-ship missiles without advance US knowledge.

The Russian Navy reportedly pulled back from the Ukrainian coast in the aftermath of the attack, in which one person was killed and 27 remain missing. The Russian side said the missile cruiser sunk due to a fire and the detonation of ammunition aboard.

The Pentagon also pushed back on another report on the US role in supporting Ukraine's killing of Russian generals.

"We do not provide intelligence on the location of senior military leaders on the battlefield or participate in the targeting decisions of the Ukrainian military," Pentagon spokesman John Kirby said earlier on Thursday.

In the port city of Mariupol an estimated 200 civilians, along with Ukrainian fighters, are trapped in the Azovstal steel plant with little food or water.

The United Nations said a new operation was underway to evacuate more people from Mariupol.

Meanwhile, the steelworks was rocked by heavy explosions on Thursday as Russian forces fought for control of it.

Russian President Vladimir Putin said Moscow was prepared to provide safe passage for the civilians, but reiterated calls for Ukrainian forces inside the plant to disarm.

Aerial footage of the plant, released on Thursday by Ukraine's Azov Regiment, showed three explosions strike different parts of the vast complex, which was engulfed in heavy, dark smoke.