An apparent mid-air collision killed another four American soldiers in Afghanistan on Monday as President Hamid Karzai questioned the reliability of the United States ahead of a run-off election.

The collision in southern Afghanistan came as NATO-led forces reported that another helicopter crashed in the northwest of the country following a raid on suspected drug traffickers.

NONEThe current year has been the most deadly for the more than 100,000 NATO and US troops fighting a resurgent Taliban since the 2001 US-led invasion ousted the Islamists' extremist regime in Kabul.

NATO's International Security Assistance Force (ISAF) said the crash in the south was currently being investigated but no hostile fire was involved.

"Four ISAF service members were killed and two others injured in the incident," it said in a statement, adding that the two helicopters had apparently collided in mid-air.

Colonel Wayne Shanks, US military spokesman in Kabul, confirmed the four dead soldiers were Americans.

The second crash happened in western Baghdis province during a joint search operation by Afghan and Western forces of "a suspected compound believed to harbour insurgents conducting activities related to narcotics trafficking".

"We are still trying to get the wounded out, we are still getting numbers from the manifest, we do not know how many were aboard the helicopter. We are still trying to get the number of wounded," said Captain Mike Andrews of ISAF.

More troops wanted

Western Afghanistan has become increasingly hostile in recent months as the Taliban spreads its tentacles across the country.

The independent icasualties.org website, which keeps a running tally of foreign troop deaths in Afghanistan says that so far in 2009, 424 have died, including 256 Americans.

The surge in the military death toll has increased pressure on US President Barack Obama as he considers a request by his top commander on the ground to deploy another 40,000 troops.

NONESome of his closest aides, including chief of staff Rahm Emanuel, have said it would be irresponsible to take a decision before a scheduled run-off election between Karzai and his former foreign minister Abdullah Abdullah on Nov 7 which follows a first round tainted by fraud.

Karzai, who came to power in late 2001 with US backing and has been pushing for the extra troops, said in a interview that he had begun to question the commitment of his traditional allies.

"Is the United States a reliable partner with Afghanistan? Is the West a reliable partner with Afghanistan?" Karzai said on CNN. "Have we received the commitments that we were given? Have we been treated like a partner?"

Karzai said a partnership to him was "where the Afghan lives are respected, where Afghan property is respected, where the Afghan traditions are respected, where we know the direction we are moving to".

The comments appeared to allude to Karzai's longstanding criticism of civilian deaths in US air strikes.

Police pelted with stones

Anti-US sentiment is on the rise in Afghanistan, illustrated Monday in Kabul when angry protests erupted for a second day running over allegations that Western troops torched a Quran.

The interior ministry said 10-15 police were injured when demonstrators started pelting them with stones.

NONEAlso in an interview with CNN, Abdullah said more troops were needed to stabilise the country but argued that Afghanistan should have been in position to ask for fewer troops after eight years of war.

"We are not there. Why? Because of the failures of the current administration in Afghanistan," he said.

Abdullah defended Obama from accusations of dithering on troop deployments, saying he was right in taking care and time for such a crucial decision, seeing what the road ahead is like.

"Any success for the US strategy in Afghanistan will depend on the credibility of your partner, on the legitimacy of your partner," he added.

- AFP