A soldier from a regiment which had 14 personnel who tested positive for drugs last month is being investigated in connection with substance abuse, the Ministry of Defence confirmed last night.

The Royal Military Police is questioning a member of the 1st Battalion of Green Howards regiment on suspicion of drug related offences.

The regiment, which is currently based at Beachley Barracks, near Chepstow, held random drugs tests last month which 14 soldiers subsequently failed.

Those soldiers are currently the subject of an internal investigation to determine whether they can remain in the army.

Of the 14, 11 tested positive for Class A drugs, one for Class B and the rest of the tests showed up Class C drugs.

A spokeswoman for the MoD said: ''A soldier has been arrested for alleged drug related offences and is assisting the Special Investigation Branch of the Royal Military Police with their inquiries.

''Obviously, it is a serious allegation. Drug misuse is incompatible with life in the armed forces and it will not be tolerated.''

She added: ''The investigation is ongoing and we wouldn't like to speculate on the outcome of it.''