Col P. Madhusudhanan, an army urologist at the hospital, says that while many sufferers can be treated successfully with a combination of drugs and psychotherapy, some do require surgical intervention. "For those who don't respond to treatment we now offer an inflatable implant which is inserted into the penis, but we see this very much as a last resort," he said.

It is easy to see why. Not only is the surgery expensive (about £3,500 per implant), the procedure involves sewing a bladder inside the patient's scrotal sac and a small pipe into his penis - the device is operated by squeezing the bladder to pump liquid into the pipe, thus creating an erection.

An earlier procedure involving the insertion of a "semi-rigid rod" had to be abandoned when army doctors found that troops were being left with permanent erections.

The hospital has fitted 12 soldiers with the collapsible penile implant, but Col Madhusudhanan admits that getting proud, battle-hardened troops to admit that they are underperforming in the bedroom has been fraught with difficulty.

"Of course there is some hesitation," said the urologist. "But to a doctor they talk quite openly. With us there is no problem about discussing their medical problem."

However, in the macho world of the Indian Army, wives are not invited to take part in the pre-surgical consultations. "Generally we don't speak to the partners," said Col Madhusudhanan. "We leave that to the soldiers."

While impotency is not uncommon in the Indian Army, doctors say that soldiers serving in the mountains of Jammu and Kashmir are particularly vulnerable because of altitude problems combined with stress.

According to Martin Wilkins, a professor of pharmacology at Hammersmith Hospital, in London, people living at high altitude produce the enzyme phosphodiesterase which restricts blood flow to the penis, causing it to droop. Phosphodiesterase also restricts the ability of the lungs to absorb oxygen, a common complaint among mountaineers. Soldiers patrolling the Line of Control between Indian Kashmir and Pakistan are often described as fighting on the world's highest battlefield "an extreme alpine environment of glaciers, ravines and snow-capped mountains rising to 21,000ft above sea level".

India and Pakistan have been locked in a bitter dispute over the control of Kashmir since the Partition of India in 1947. Although the Indian Army is reluctant to reveal any operational details of its deployment in Kashmir, Pakistan claims that India could have as many as 700,000 troops stationed in the disputed province.

George Fernandes, the Indian defence minister, can only hope that altitude-induced impotency is not spreading along the front line in Kashmir. Otherwise he might be looking at an unforseen - and perhaps embarrassing - blow to India's already massive defence budget