Fuel worth more than £250,000 has been stolen from a high-security Royal Navy base.

The fuel was siphoned from a tanker at HMNB Devenport in Dartmouth.

It was intended to fill the generators fitted to HMS Bulwark – a 19,560 tonne assault ship.

The thieves broke into the base and stole the diesel owned by Babcock International.

An investigation is under way after diesel reported to be worth more than £250,000 was stolen from a high-security Royal Navy base.

The theft happened six months ago but has only just come to light.

The Sun newspaper reported “the heist ran for weeks” and “most of the diesel has been flogged on the black market”.

Civilian guards are said to have raised the alarm during a spot check on a tanker being driven by a Babcock International driver as the vehicle left the base.

Babcock International is investigating the theft with the Ministry of Defence Police.

A Ministry of Defence spokesman said:

“The Ministry of Defence is aware of an incident last year involving the alleged theft of fuel from a contractor within HMNB Devonport.

“There was no disruption to defence operations and the Ministry of Defence has no further comment.”

A spokesman for Babcock International declined to comment.