KABUL: The number of US soldiers killed in the Afghan war in 2010 is the highest annual toll since the conflict began almost nine years ago, according to an AFP count Wednesday.

A total of 323 US soldiers have been killed in the Afghan war this year, compared to 317 for all of 2009, according to a count by AFP based on the independent icasualties.org website.

Foreign forces suffered a grim spike in deaths last month as the Taliban insurgency intensified, with NATO confirming on Wednesday that a sixth US soldier was killed on one of the bloodiest days this year.

At 490, the overall death toll for foreign troops for the first eight months of the year is rapidly closing in the number registered in all of 2009, which at 521 was a record since the start of the war in late 2001.

A total of 80 international soldiers died in the Afghan war last month, 56 of them Americans.

In all, 1,270 US troops have lost their lives since the conflict began with the US-led invasion of Afghanistan following the September 11 attacks on the United States in 2001.

US President Barack Obama on Tuesday warned that the United States faced a "very tough fight" in Afghanistan, with more casualties and "heartbreak" to come.

"We obviously still have a very tough fight in Afghanistan," Obama told troops in Texas as the United States marked the formal end of combat operations in Iraq.

"We have seen casualties go up because we are taking the fight to Al-Qaeda and the Taliban," Obama said. "It is going to be a tough slog."

NATO`s International Security Assistance Force (ISAF) confirmed that a sixth US soldier died on Tuesday, killed in an insurgent attack in the south of the country.

This followed the previously announced deaths on Tuesday of another five US soldiers, four of them killed in a roadside bomb attack, which is the hallmark of the Taliban fighting style.

Twenty-five Americans have died since Friday.

Military leaders say the spike in deaths reflects the injection of additional troops into the Afghan theatre, which leads to a higher number of battlefield engagements with Taliban-led insurgents.

US General David Petraeus, the commander of US and NATO forces in Afghanistan, said Tuesday that deployments would reach their full strength of 150,000 within days.

On Monday, eight NATO troops -- seven Americans and an Estonian -- were killed in bomb attacks in southern Afghanistan.

Icasualties.org is constantly updating its figures as soldiers wounded in battle die of their injuries after they have been evacuated from Afghanistan, sometimes days or weeks later.

BDST: 11:15 HRS, September 1, 2010