A ROYAL Navy aircraft carrier failed to set sail for a Nato exercise just a week after its sister ship had to pull out due to a mechanical fault.

HMS Prince of Wales was due to replace HMS Queen Elizabeth in Exercise Steadfast Defender in the largest Nato exercise since the Cold War.

However, the £3 billion warship has remained in Portsmouth and the harbour mouth has been reopened to normal marine traffic.

The Ministry of Defence (MOD) has confirmed the departure has been “postponed” after hundreds lined up to watch the carrier’s scheduled departure at 12.15pm on Sunday.

However, after MOD police boats secured the area and the harbour mouth was closed, the channel was reopened and the crowd dispersed.

Last Sunday, HMS Queen Elizabeth was forced to cancel its deployment to the exercise off Norway after an “issue” was found with a coupling on the starboard propeller shaft.

HMS Prince of Wales has previously faced issues, having broken down off the Isle of Wight in 2022 when it also suffered a malfunction with a coupling on its starboard propeller.

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The MOD previously said the issued were “separate and not linked”.

HMS Prince of Wales was taken to Rosyth in Fyfe to undergo repairs which took nine months to complete.

Speaking to LBC, security minister and Tory MP Tom Tugendhat suggested it was “not acceptable” that the HMS Prince of Wales remains sitting in dock.

Asked what happened, he said: “I’m afraid it’s not something I can explain, that’s a matter for the MOD and I’m going to have to ask some questions about it.

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“But I’m sure the First Sea Lord is looking at this right now. Admiral Key has commanded an aircraft carrier in the past and will no doubt be all over the details of this and making sure they set sail as soon as possible.

“It isn’t acceptable that we have such expensive and important items of kit sitting in dock when they should be out defending our interests abroad.”