Britain’s Royal Navy is in such a poor state that it will struggle to deal with the country’s biggest threats unless it gets new ships fast, a committee of MPs has said.

In a scathing report, the Defence Select Committee said the state of the navy was a “national disgrace”, with committee chair Julian Lewis warning that the number of vessels was “pathetically low”.

If defence cuts continue, the committee warns, Britain could be left with fewer than 19 frigates and destroyers. MPs say any drop below that number would be “completely unacceptable” and leave the UK vulnerable to external threats from the Middle East or Russia.

A total of 13 frigates are scheduled to leave service at a rate of one a year between 2023 and 2035, with MPs expressing “serious concern” about the funding a political will be build their replacements.

“The United Kingdom will then lack the maritime strength to deal with the threats we face right now, let alone in the future. We are putting the [Ministry of Defence] on notice that it must not let this happen,” Mr Lewis added.

The committee said: “As an island nation, the importance of the Royal Navy to UK defence must not be underestimated.

“Our starting point in this report is our conviction that the current number of frigates, destroyers and personnel inadequately reflects the potential threats and vulnerabilities facing the UK and its interests overseas.”

Escort vessels have also been “severely in decline”, Mr Lewis added.

“The fleet is now way below the critical mass required for the many tasks which could confront it, if the international scene continues to deteriorate,” he said.

“What remains of our surface fleet now faces a prolonged period of uncertainty, as the frigate class is replaced in its entirety and all our destroyers undergo urgent, major remedial work on their unreliable engines.”

The committee attacked the Ministry of Defence for what they called “extraordinary mistakes” in design of the engines for Type 45 destroyers.

“It is astonishing that the specification for the Type 45 did not include the requirement for the ships to operate at full capacity – and for sustained periods – in hot regions such as the Gulf,” they said.

“The UK’s enduring presence in the Gulf should have made it a key requirement for the engines. The fact that it was not was an inexcusable failing and one which must not be repeated.

“Failure to guarantee this would put the personnel and ships of the Royal Navy in danger.”