The group, which includes two Lance Corporals, were among 150 soldiers tested for drugs at west London's Chelsea Barracks several weeks ago.

The 10 people have been confined to barracks pending a review of their case.

The regiment is famous for ceremonial duties it carries including the state opening of Parliament.

A Ministry of Defence (MoD) spokesman said: "The Army recognises a small minority of soldiers do take drugs but drugs misuse is not widespread and we have a zero tolerance policy on drug taking."

He could not say which drugs had been detected.

The drugs were found in urine samples from nine of the Queen's mounted bodyguards and one soldier from a unit attached to the Household Cavalry Mounted Regiment.

They face the sack if they are found to have breached Army regulations on drugs, the MoD spokesman said.