The armed forces were under fire yesterday as it emerged that at least four servicewomen have had breast enlargement operations at a military hospital since the start of the year.

The women went under the knife for implants at the Services' Royal Hospital Haslar in Hampshire, the Ministry of Defence confirmed. It defended the operations, which can cost thousands of pounds, saying they were medically necessary.

However, Iain Duncan Smith, Conservative shadow defence secretary, said the situation was ''ridiculous'' and brought a whole new meaning to the phrase ''second front''.

He said: ''This is happening at a time when money is short in the armed forces and there are shortages in soldiers, air crew and ships' equipment. This Government seems to be squandering money on things that will have little effect on fighting capability even if they enhance morale.''

But an MoD spokesman said: ''We are not treating our servicewomen any differently than they would be treated as civilians by the NHS. These are only done for medical reasons not for aesthetic reasons. If they have got some sort of deformity or psychological reasons these are taken into account and it is only done if recommended by a doctor.''

The true number of breast enlargement operations among servicewomen is likely to be even higher.

''We have got no central records of them,'' an MoD spokesman said.

Last month Lance Corporal Roberta Winterton, 20, was given her marching orders by the army when she posed topless for a tabloid newspaper, the first serving soldier to do so.

Meanwhile, it was reported that women with breast implants are up to three times more likely to die from lung or brain cancer than those without. The findings come after a US study of 13,500 women who received implants