More than 10,000 British soldiers are unfit for frontline duty as the pressure of supplying troops for years of conflict in Iraq and Afghanistan takes its toll on the army, the Sunday Telegraph reported.

The newspaper said the Ministry of Defence admits that 8,500 soldiers from the 59,000-strong "Field Army" -- units such as tank, artillery and infantry regiments --- are classified as unfit to serve at the front.

When other soldiers classified as unfit from the overall 101,800-strong army are taken into account, the total figure is likely to exceed 10,000, said the newspaper, which is traditionally close to the armed forces.

The figure of one in 10 soldiers classified as unfit for operations is the highest since the start of the Iraq war in 2003. Britain has been Washington's staunchest ally in Iraq and about 4,000 British troops are currently based there.

Prime Minister Gordon Brown announced Monday Britain was sending an additional 230 troops to Afghanistan, which will boost its contingent to 8,030 by early next year -- its highest level since operations began in 2001.

British troops are stationed in violence-hit southern Afghanistan, where they are fighting Taliban extremists.

Nine British soldiers, including the first British woman killed in action in Afghanistan, have lost their lives in the past two weeks.

US commanders have repeatedly called for other NATO countries to shoulder the burden of operations in the lawless south.

Patrick Mercer, a lawmaker from the opposition Conservatives and a former army officer, told the Sunday Telegraph that British soldiers were exhausted.

"The problem is that incessant operations are wearing down the troops' resilience," he said.

"They are not being given the time between operational deployments to catch their breath, let alone to recover from the effects of exhaustion, illness and wounds.

"There are not enough combat troops in the army for the job they are being asked to do."