“It’s all a matter of money,” Mr Drax added. “If we are going to ask these brave men to do these things, the least we could do is provide them with the facilities to do it.”

Johnny Mercer, the former veterans minister, described it as a “farce”. He told The Telegraph: “You either commit to two tier 1 SF units or you don’t. The disinvestment in the Special Boat Service over recent years is a disgrace.”

Mr Mercer questioned why such “suitable facilities” for the Special Forces units were not budgeted for.

One Navy source confirmed to The Telegraph that “the pool is shut and out of bounds” and has been closed “for quite some time”.

“The long-term plan is to build an Aquatic Centre but they are still seeking funding,” they added. “Currently, the solution is that they go to Portland harbour and train there.”

Tobias Ellwood, the chairman of the Commons defence select committee, warned that if the UK is to retain the status of having elite forces “who are the best in the world”, then it is “critical we invest in upgrading key facilities such as the aquatic centre that is pivotal to so much of the SBS’s training”.

A Ministry of Defence spokesman said: “There is a pool on the unit’s camp but it requires refurbishment. An aquatic centre would, of course, provide the best possible facilities, but such investments much be prioritised with improvements to wider infrastructure, equipment, and accommodation.”