June 16 (Reuters) - A Moscow oil refinery halted operations after a Ukrainian drone attack on Tuesday, two industry sources said.

The strike, claimed by Ukraine, sparked a fire and damaged a primary refining facility CDU-6 able to process some 21,400 metric tons of oil a day, the sources said, or 53% of the refinery's capacity.

The refinery is expected to resume operations soon at its second primary unit, capable of processing 18,800 tons of oil per day, the sources, who spoke on condition of anonymity because they were not authorised to speak publicly, said.

Local emergency services said earlier on Tuesday that a fire at the refinery had been put out and had not affected operations. Moscow Mayor Sergei Sobyanin said a facility at the site had been damaged, without giving further details.

The refinery is in the southeastern part of Moscow and helps to supply fuel to Russia's capital.

Gazpromneft, which owns the refinery, did not immediately reply to a request for comment.

The sources said the refinery processed 11.6 million metric tons of crude oil in 2024 - or some 230,000 barrels per day - and produced 2.9 million tons of gasoline, 3.2 million tons of diesel and 1.3 million tons of bitumen.