THE MOUNTAINS of California mimicked the hilly terrain of Afghanistan when Royal Marine Reservists from Plymouth carried out a major military exercise.

About 80 reservists from the UK embarked on a specialist high-altitude training exercise in the Sierra Nevada mountains, ahead of the next deployment to Afghanistan in April.

The part-time soldiers worked out of the United States Marine Corps' Mountain Warfare Training Centre at Pickel Meadows, north of Yosemite National Park.

As part of Exercise Commando Strike, the men trained at altitudes of 9,000 to 12,000 feet where oxygen is limited.

They carried loads weighing up to eight stone in temperatures of almost 100 degrees.

The California mountains are the only place in the world that suitably replicates the arid, high terrain of Afghanistan, with peaks three times higher than Ben Nevis.

The mountains in the UK aren't high enough to conduct high-altitude training, where the air is much thinner, making it harder to breathe even when doing normal activities.

A spokesman for the reservists said: "The reservists learned new skills such as mule packing, which is usually carried out by US marines.

"They also practised vertical assaults and river crossing skills which will allow them to assist in Royal Marines operations anywhere in the world.

"Their final training exercise, which lasted four days, involved tracking a fictional Afghanistan terrorist in the mountains."

It was devised by Captain Stuart McLean, at training officer at RMR Bristol, using experience he gained while deployed in Afghanistan on Operation Herrick 9 last year.

Meanwhile, Lieutenant Steve Corbidge defended the decision to take the men to the US on their annual exercise.

He said: "Because of their civilian occupations these guys can only deploy for 14 days and the arid environment means we have temperatures of up to 95 degrees.

"I've got to give these guys opportunity to acclimatise to both the altitude and also the temperatures, so you do need an extended training period to take them up to the level that they are ready to join their regular units.

"We could have done that in the UK but we would not have had the opportunity to train in this environment with the US Marine Corps and the benefits of here are far, far greater than we would experience in the UK."

Around 10 per cent of the RMRs are working with the Regular Corps on long-term attachments in all of the Royal Marines regular units.