There are around 4,000 UK troops stationed in Afghanistan

Des Browne was giving evidence to MPs a day after announcing 900 more UK troops were being deployed to Afghanistan.

Mr Browne said the UK's role in the troubled country was a "noble cause".

Meanwhile, he said UK forces will hand over control of the British-run Muthanna province in Iraq to authorities there later this week.

Help needed?

He said he expected an announcement from the Iraqi government on Thursday. British troops stationed there will be redeployed.

Mr Browne said he would be disappointed if announcements on two further areas did not follow relatively soon.

In his first appearance before the Commons defence committee as secretary of state, Mr Browne was quizzed about military chiefs having to "cobble" companies from different regiments because of "overstretch".

That was a charge he rejected, although he said there was "stretch".

He also said he did "not accept it is necessary for other Nato countries to provide help" in Afghanistan's Helmand province where six UK soldiers have been killed in the past month.

More helicopters

His announcement of a further deployment to Afghanistan will boost troop levels to 4,500.

The forces will head for Helmand to help security and reconstruction efforts.

In a Commons statement on Monday, Mr Browne said 320 engineers from 28 Regiment Royal Engineers would be used to "accelerate the reconstruction effort".

A company from 3 Commando Brigade Royal Marines would provide force protection for them and those deployments would take place from September. More helicopters would also be provided.

An extra infantry company, taken from the 2nd Battalion The Royal Regiment of Fusiliers, would also provide more mobile forces.

Reservists

And two platoons from the 1st Battalion, The Royal Irish Regiment would provide additional force protection.

The defence secretary said there would also be a "small increase" in HQ staff and medical and logistical support.

And 450 reservists were being called up to fill 400 posts "in theatre".