Claims of bullying at Catterick training barracks in North Yorkshire came to light during an undercover investigation by the BBC in September. Recruits complained of being "battered", punched and kicked by instructors. One claimed his shoes had been urinated on by an officer.

Junior Defence Minister Kevan Jones said yesterday the Army Prosecuting Authority had directed that four people should face a military trial.

Mr Jones said the four individuals were already being investigated by the Ministry of Defence before the documentary was broadcast. Defence sources said the four people were all male training instructors.

In a Commons written reply to Labour's Joan Humble (Blackpool N and Fleetwood), Mr Jones said: "We were already aware of some of the allegations made by the BBC in its The Undercover Soldier documentary in September.

"A Royal Military Police (Special Investigation Branch) investigation had been initiated in February.

"For those we were not aware of, an RMP(SIB) investigation was launched as soon as the BBC made us aware of their concerns. These investigations are continuing."

He went on: "The Army Prosecuting Authority has now directed that four individuals, who were the subject of allegations of which we were already aware and which we were investigating, should face trial by court martial."

Five training instructors were suspended as the BBC prepared to screen its documentary on September 18.

Defence sources at the time said three officers had already been suspended at Catterick before they were made aware of the television investigation.

But another two were suspended after they received the report from Russell Sharp, who went undercover as an infantry recruit at the base for six months.

The Government had previously pledged to crack down on bullying in the Army following the scandal at Deepcut involving the deaths of four teenage recruits between 1995 and 2002.