One of the Royal Navy’s multi-billion pound nuclear-powered submarines has been beset with catalogue of design problems and construction failures, it emerged last night.

HMS Astute, the first of seven new submarines to be built at a cost of £9.75bn, is reportedly too slow, is subject to leaking and is rusty in parts.

The boat, lauded as the most sophisticated Navy submarine, cannot race to emergencies or away from an attack – considered an essential requirement – because it is unable to reach its intended top speed.

It also cannot maintain the more than 30 knot speed with the Navy new aircraft carriers, which the submarines protect, because of what sources described to The Guardian as a "V8 engine with a Morris Minor gearbox".

Other problems reported in recent months include flooding during a routine dive, corrosion in parts – despite being new – nuclear reaction monitoring instruments being the wrong type of lead and concerns the periscope is flawed.

"These problems are much more significant, than the niggles and glitches expected to arise during working up of a new class of nuclear-powered submarine,” said John Large, an independent nuclear safety analyst and specialist engineer.