Russian missile cruiser Moskva is moored in the Ukrainian Black Sea port of Sevastopol, Ukraine May 10, 2013.
Russian missile cruiser Moskva is moored in the Ukrainian Black Sea port of Sevastopol, Ukraine May 10, 2013. Reuters / STRINGER

The United States believes the Russian warship Moskva is still dealing with a fire and the ship is believed to have experienced significant damage, a senior U.S. defense official said on Thursday.

The warship, a Soviet-era missile cruiser, is still believed to be afloat and the United States is under the assumption that the cruiser is heading to Sevastopol, the official said.

"Our assessment is that she still appears to be battling a fire on board," the official said.

Russia said the crew of the warship had been evacuated and measures were being taken to tow the stricken ship back to port, after an explosion of ammunition on board that Ukraine said was caused by a missile strike.