It is “not acceptable” that Royal Navy aircraft carrier HMS Prince of Wales is sitting in dock when it should be out “defending our interests abroad”, security minister Tom Tugendhat has said.

The vessel’s departure from Portsmouth on Sunday was postponed at the last minute as it was about to set sail to replace its sister ship, HMS Queen Elizabeth, which was forced to cancel its own deployment a week ago.

The £3 billion warship had been expected to take part in the largest Nato exercise since the Cold War, involving more than 40 vessels, but final checks detected an “issue” with the starboard propeller coupling.

Since the cancellation was announced, the crew and base workers have been preparing HMS Prince of Wales to take over HMS Queen Elizabeth’s role in Exercise Steadfast Defender off Norway.

Asked what had happened to HMS Prince of Wales on Sunday, Mr Tugendhat told LBC: “I’m afraid it’s not something I can explain – that’s a matter for the MoD (Ministry of Defence), and I’m going to have to ask some questions about it.

“But I’m sure the First Sea Lord is looking at this right now. Admiral (Sir Ben) 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.”

An MoD spokesman confirmed HMS Prince of Wales’s sailing had been postponed but did not give a reason for the last-minute decision.

He said: “The aircraft carrier HMS Prince of Wales is due to sail from Portsmouth soon, subject to suitable tide and weather conditions.”

HMS Prince of Wales is now expected to set sail on Monday February 12.

Mr Tugendhat also rejected the suggestion that the warship can only sail on a sunny day when the tide is going the right way.

Asked whether the aircraft carrier can only be used in such conditions, he told LBC: “That is absolutely not correct.

“Our warships are capable of operating in practically all weathers… the reality is we have a completely capable Navy with some extraordinary sailors who are able to equip and deploy our vessels around the world.

“And you can see them in operations today, fighting the Houthis in the Red Sea, but also defending our interests around the world.”

Meanwhile, HMS Queen Elizabeth is undergoing investigation.

A Royal Navy spokesman said: “On completion of initial investigations, HMS Queen Elizabeth will sail for Rosyth in Scotland so any necessary repairs can be carried out in due course.

“The cause of the issue with HMS Queen Elizabeth is wear and tear of her starboard propeller shaft coupling.”