Ben Wallace, secretary of defence, and the heads of the Navy, the Royal Air Force and Strategic Command were all ordered to isolate for a 10-day period last week, the Telegraph newspaper reported late on Sunday.

It added that the head of the Army, General Mark Carleton-Smith, also spent the weekend in self-isolation as he awaited the results of a Covid test.

They had all come into close contact with the Chief of the Defence Staff Nick Carter at a summit in Shrivenham in southern England on Thursday.

The meeting came a day after Britain and Russia squared up over a naval incident off the coast of Crimea, as Moscow said it had fired warning shots at a Royal Navy destroyer in Black Sea waters it claims.

But the UK's defence ministry swiftly denied that any warning shots were fired, saying it believed Russia was "undertaking a gunnery exercise" and had provided prior warning to shipping in the area.

The military heads are expected to conduct meetings and other business remotely after they were informed by the state-run National Health Service's Test and Trace service they had come into contact with a positive case.