More than one in 20 Ministry of Defence police officers – the men and women charged with protecting the UK’s key defence and nuclear assets – are under formal investigation for a range of possible offences.

Figures released under the Freedom of Information Act show that 170 officers – more than 6% of the 2,700 employed by the MoD – are being investigated for a raft of possible disciplinary and criminal offences.

Of these, 86 are being investigated for neglect of duties, 43 for their general conduct, five for harassment and bullying, and a similar number for aggression. Others are facing possible firearms, sexual conduct, drugs and fraud charges.

The large number of officers – all of whom are weapons-trained and most of whom will be armed while on duty – who are being investigated is a concern, given the crucial nature of their role in protecting the UK’s infrastructure at more than 120 sites around the UK. It also suggests that investigations into the force are on the rise. Two years ago, just 50 MoD officers were reportedly being investigated.

Any allegation of criminal or disciplinary conduct is taken very seriously MoD police spokesman

The Ministry of Defence police (MDP) protects sensitive sites such as the Faslane and Coulport military bases, the atomic weapons sites at Aldermaston and Burghfield, GCHQ, the Portsmouth and Devonport naval bases, defence munitions establishments and the MoD’s Whitehall offices. They also oversee the transportation of defence nuclear materials in the UK.

The investigations come at a difficult time for the force. Its budget has been halved from £360m to £180m and it faces losing 20% of its personnel and up to 50% of its stations by 2016.

A spokesman for the force said: “The Chief Constable expects all of his officers and staff to behave with the highest levels of professionalism and integrity, and any allegations of criminal or disciplinary conduct are taken very seriously.

“Where such allegations are made, they are fully investigated and, if substantiated, the MDP will respond accordingly with criminal and or disciplinary action.”