Grant Shapps has insisted the Red Sea shipping crisis has not escalated amid plans to send a new warship to the region, while also playing down recruitment issues in the Royal Navy.

The Defence Secretary told MPs that HMS Richmond, a type 23 frigate, is only being deployed to the Gulf region to replace British vessels already patrolling the Red Sea.

The UK has already sent HMS Diamond and HMS Lancaster to the region to protect container ships from assaults by the Houthis, an Iran-backed militant group from Yemen which has disrupted and attacked trade vessels trying to pass through the region in recent weeks.

A US-led coalition, Operation Prosperity Guardian, has been protecting trade ships as they journey through the region and towards the Suez Canal and Europe.

Addressing the “intolerable situation of the Houthis closing international waterways”, Mr Shapps said: “We call for the Iranian-backed Houthis to immediately cease these attacks.

“The Houthis will bear (the) responsibility of the consequences should they ignore these warnings.”

The Defence Secretary also told MPs that reports of an increasing number of sailors leaving the Navy should not impact the UK’s ability to carry out maritime operations.

In the Commons, shadow defence secretary John Healey said: “He has announced today but hasn’t mentioned to the House that HMS Richmond is now sailing to the Gulf. In light of these escalating tensions, what other Royal Navy ships has he put on standby for the region?”

Mr Shapps said: “Richmond is actually sailing to the region because both Diamond and HMS Lancaster are already there and eventually will need to be swapped out.

“So it is not an escalation in terms, but I do want to repeat to him, to the House and to the country that we will not tolerate trade being impacted globally in the manner in which the Houthis are currently impacting it.

“It will have ramifications on everybody’s bills and the flow of free trade and goods and it must come to a halt.”

SNP defence spokesman Martin Docherty-Hughes, meanwhile, said it is right the Government take steps to support Prosperity Guardian but asked: “I wonder if he can advise the House how sustainable this and future joint operations will be when we have seen an increasing number of sailors leave the service, and have seen the intake to replace them in the 12 months to March 2023 plunge by 22.1%?”

The Telegraph newspaper said the Navy has been forced to turn to private contractor Serco in order to recruit deckhands because of a lack of new sailors.

Mr Shapps said: “The first thing I should say is I am confident we will be able to continue or increase our actions.

“It is true that we actually complete all our operation requirements at the moment, but he is right to say there is a very tight labour market and I think that is actually a subject for celebration in this House that we are seeing such low sustained unemployment even through some pretty turbulent times.

“But of course we will be redoubling our efforts to ensure that all of our services can recruit the people that they need.”

Elsewhere, defence minister James Cartlidge assured MPs no final decision has been made after reports that two assault ships, HMS Albion and HMS Bulwark, could be retired to free up sailors for other vessels amid the recruitment crisis.

Mr Cartlidge told MPs: “What I would say is no final decision has been made on these platforms. I know there has been a lot of coverage in the press and a lot of chatter inevitably. I know how important they are to our service personnel but I want to reassure him that we are looking at this in the round.”

Conservative former minister Sir Julian Lewis said: “A short-sighted, militarily illiterate manoeuvre totally at odds with strategic reality’ was how the Defence Committee described in February 2018 the proposal to retire HMS Albion and HMS Bulwark ahead of their anticipated lifetime dates of 2033 and 2034.

“May I advise and warn the Defence Secretary not to be blindsided by those people who are raising this again after a change of Secretary of State for Defence.”

Mr Shapps reiterated that “no decision has been made”.

Conservative former defence minister Sarah Atherton said: “There are obvious questions raised about Britain’s future amphibious capability, a capability used so admirably during the Falklands War.”

She added: “Our Royal Marine Commandos are an asset we cannot afford to lose.”

Mr Shapps said: “The Royal Marines are absolutely essential. I have asked the First Sea Lord to provide a plan for how their excellent work is taken forward.”