THE Ministry of Defence has insisted new lightweight body armour provided for troops on the front line in Afghanistan is fit for purpose and saving lives.

In a robust defence of the new kit called Osprey Assault, designed for forces fighting on the front line, the MoD said it offered "excellent levels of protection".

The news came as it was announced that British troops were to take part in a huge coalition push against the Taliban, Operation Moshtarak, which Defence Secretary Bob Ainsworth warned may result in casualties.

On Sunday, two more British servicemen were killed while on patrol in Helmand, taking the number of UK personnel who have died in Afghanistan since 2001 to 255 – the same number as were killed during the 1982 Falklands War.

More Westcountry troops are due to deploy to Afghanistan this spring as part of 4 Mechanised Brigade, which begins its six-month tour of duty in April.

Taunton-based 40 Commando and elements of squadrons from RNAS Yeovilton in Somerset and RNAS Culdrose in Cornwall form part of the brigade.

Meanwhile, the Government dismissed criticism of the new body armour issued to troops on the front line.

Osprey Assault has been designed to be lighter and more mobile than standard issue Osprey armour.

But there had been concerns raised about the antiballistic plates fitted to the front and back of the vests designed to protect the vital organs.

The MoD said a new type of plate had consistently failed tough tests and had not been approved for use in the Osprey Assault vests, with prototype versions never leaving the testing range.

As a result, the vests, one part of a set of four in Osprey Assault which are part of the £16 million upgrade, were sent out to British troops without plates.

Instead, troops are being asked to transfer the plates from the ordinary issue Osprey vests into the Assault vests.

This involves removing a rubber coating to make it thin enough to fit in the pocket designed for the vest.

A MoD spokesman said removing the sleeve made the plates one-third thinner, but it did not diminish the antiballistic capabilities.

The rubber coating was designed to stop it shattering on impact and potentially creating further hazards. He said the pocket for the plate in the new Osprey armour would do this just as well.

"Body armour is saving lives on the front line," said the spokesman.

"Osprey and Osprey Assault offer the same excellent levels of protection, but the newer Osprey Assault is more comfortable. We insist on the very highest standards for our troops' kit and, regrettably, delays can occur if manufacturers fail our tough tests."

British troops are currently gearing up for Operation Moshtarak, designed to force Taliban militants out from strongholds they have established in the fertile Green Zone at Nad Ali in Helmand.

It is estimated that 4,000 UK service personnel will take part in the offensive which will involve up to 15,000 coalition forces.

This would dwarf the largest British military operation so far in Afghanistan, Operation Panther's Claw, which last year left 10 UK soldiers dead and many others seriously wounded.

Military commanders believe publishing the scale of the operation beforehand will persuade less-committed members of the Taliban to lay down their arms.