The Ministry of Defence have denied that the Royal Navy’s fleet of attack submarines are all currently out of action.
Britain’s seven ‘hunter-killer’ vessels were reported to to be ‘non-operational’ as they undergo repairs and maintenance.
However, an MOD source told the Telegraph the reports were "categorically not true."
Theresa May was said to have been kept in the dark by Defence chiefs, the Sun reported.
A Whitehall source told the newspaper: “No one is being honest about the scandal.”
It was reported that five of the fleet, including one of the new type, are having refits or maintenance after breaking down.
Sources said the three new Astute class subs, which cost £1.2billion each, are beset by technical problems.
An MOD source said: "This story is categorically not true- there are operational, capable and ready attack submarines.
"Where they might be is clearly sensitive operational information that the MOD will not comment on."
It comes after Britain's ability to defend itself against a major military attack was called into question after an investigation found Navy warships are so loud they can be heard 100 miles away by Russian submarines.
A Royal Navy spokesman said: "We don’t comment on specific submarine operations.
"Britain has a world-class fleet, the Royal Navy continues to meet all of its operational tasking, deploying globally on operations and protecting our national interests as Britain steps up around the world."