The Royal Navy aircraft carrier HMS Queen Elizabeth has set sail from Portsmouth following two subsequent days of delays caused by “fewer than 10” crew members testing positive for coronavirus.

Crowds lined the harbour walls in Old Portsmouth on Wednesday afternoon to wave off the warship with more than 60 people packing the Round Tower – the traditional viewing point to see off Navy ships.

The carrier was scheduled to leave Portsmouth Naval Base on Monday afternoon for training exercises, but the departure was put on hold at the last moment.

It was expected to sail again on Tuesday, but this departure was also cancelled.

A MoD spokesman confirmed that “fewer than 10” members of the 1,000-strong crew had tested positive for coronavirus and had been taken ashore to be put into isolation in barracks.

Other sailors who had contact with their infected crewmates will isolate on board the 65,000 tonne ship.

On Wednesday, a person swimming across the main shipping lane at the harbour’s mouth was intercepted by a military police boat and ordered to swim to the shore.

The area is closed to all water traffic to enable the carrier to exit the narrow harbour safely.

The carrier had to postpone its sailing earlier this year after two crew members tested positive for Covid-19 in April.

The ship is set to carry out training exercises at sea before returning to base for supplies ahead of departing for major international exercises including the embarkation for the first time of both US and UK F35 Lightning jets.

It is aiming to declare strike carrier capability later this year ahead of its first operational deployment in 2021.