The US defence secretary yesterday asked Congress to approve nearly $190bn (£95bn) more in spending for the wars in Iraq and Afghanistan.

Robert Gates said the Bush administration sought the money for more training and equipment for the US military, including new armoured vehicles that give extra protection to troops against bomb blasts.

More money was also needed to train and equip Iraqi security forces as well as to "consolidate our bases in Iraq", Gates said.

In asking for the money, Gates said he was aware of the controversy surrounding the unpopular war. Since 2001, Congress has appropriated $602bn (£301bn) for the conflicts in Iraq and Afghanistan.

However, he said US troops had done far more than had been asked of them, adding: "Like all of you, I always keep our troops - their safety and their mission - foremost in my mind every day."

The biggest chunk of the new request would go for force protection, including $11bn for fielding 7000 more mine-resistant vehicles, which have V-shaped hulls to disperse the impact of blasts.

The Pentagon is also investigating the oversight of security contractors it employs in Iraq after a fatal shooting incident in Baghdad involving other contractors employed by the State Department.

Gates has sent a five-person team to Iraq to review the contractors' operations.

The State Department is investigating a shooting incident earlier this month in which 11 people were killed while contractors from the US firm Blackwater were escorting an embassy convoy through Baghdad.

The contractors worked for the State Department. The Pentagon employs 7300 security contractors in Iraq, but none from Blackwater.

Iraq has said it would review the status of all security firms after the Blackwater shooting incident which incensed Iraqis who see the tens of thousands of private security contractors as private armies that act with impunity.

As violence continued in Iraq yesterday, with 59 people across the country killed in bomb attacks and more than 120 wounded in an al Qaeda campaign of violence coinciding with Ramadan, the US Army's chief of staff warned it was "unsustainable" to keep troops on a rota of 15 months in combat in Iraq and Afghanistan, with only 12 months at home between deployments.

General George W Casey told the Congressional Armed Forces Committee that it was imperative soldiers had longer breaks from battlefield duty to reduce the psychological and physical toll on manpower and family life.

He also said lawmakers should be prepared to fund replacements and repairs for equipment worn down by constant use in action.

Stocks of everything from Abrams tanks to Bradley infantry fighting vehicles and ammunition had been plundered to keep units operational at the expense of a reserve for potential crises elsewhere.

The US National Guard, the American equivalent of Britain's Territorial Army, has also been stripped of much of its fighting equipment to keep regular front line units operational.

One senior officer said: It's no secret that our current ability to project power across the globe in meaningful numbers in the event of a sudden crisis is zero."