The US president plans to ask congress for an extra $33bn to fight the wars in Afghanistan and Iraq this year, defence officials say.

The money, mainly for the deployment of 30,000 additional troops to Afghanistan and other war costs in the 2010 fiscal year, would come on top of Barack Obama's expected request to increase the Pentagon's overall budget in fiscal 2011 to a record $708bn, the officials said on condition of anonymity.

Fiscal 2010 defence department funding, including war costs in Afghanistan and Iraq as well as military construction, already comes to $660bn without the $33bn emergency funding request.

The budget for fiscal 2011, which begins on October 1, is expected to be released by the White House only next month, but military officials have suggested it would top $700bn for the first time.

Despite the proposed increase for next year, analysts say Pentagon procurement is likely to remain under pressure, and more weapons-buying programmes may be cut, because personnel and healthcare costs are taking up an increasing chunk of the overall Pentagon budget.

Vital national interest

Last week, Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, said he expected Pentagon funding to begin to drop within a couple years because of the country's economic woes.

Despite that, Obama and his defence secretary, Robert Gates, face a major challenge trimming even a limited number of weapons programmes over the objections of legislators who see them as a source of skilled manufacturing jobs.

After more than two months consulting military leaders, ambassadors and national security advisers in a review of US strategy in Afghanistan, Obama announced last month that he would send an extra 30,000 troops to the war.

The deployment, he said, was in the "vital national interest" of the US, and would create a situation allowing the US to start withdrawing its troops in mid-2011.

He said the additional troops "are the resources that we need to seize the initiative" and bring the eight-year long war to a "successful conclusion".

The increased deployment will increase the US military presence in Afghanistan to around 100,000.

The number of civilians killed in war-related violence in Afghanistan touched 2,412 last year, the highest number since the 2001 US-led invasion, the UN has said.

A report by the UN mission for Afghanistan pointed to the "intensification and spread of the armed conflict" in what was also the deadliest year for foreign forces, with 520 troops killed.

It said 70 per cent of civilian deaths were caused by Taliban attacks, while 25 per cent were killed by pro-government and foreign forces - a 28 per cent reduction in deaths caused by Western forces since 2008.

The remaining 135 civilians were killed in violence not attributable to the conflicting parties, the UN said in its report.

'Excessive use of force'

The UN found most deaths attributed to pro-government forces were killed in air raids as well as search and seizure operations.

"These often involved excessive use of force, destruction to property and cultural insensitivity, particularly towards women," it said.

But it said that a change in Nato command structure had helped reduce the number of non-combatant deaths by coalition troops.

US General Stanley McChrystal, the commander of the foreign forces in Afghanistan, has made minimising civilian deaths and injuries a central tenet of his counter-insurgency strategy, ordering reduced air attacks as one way of achieving this objective.

The UN report said the change in Nato forces' command structure, "specific steps to minimise civilian casualties" and "a new tactical directive" by the force contributed to the reduction in non-combatant deaths.

Civilian casualties are a source of tension between the Afghan government of Hamid Karzai, the Afghan president, and the international forces fighting the insurgency.

Recent incidents, such as the deaths of 10 civilians including eight teenagers in eastern Kunar province in an authorised but non-military US operation, have seen Afghans take to the streets to protest against the presence of foreign troops.