Five US troops fighting Islamist insurgents in southern Afghanistan were killed in a helicopter crash in bad weather, the coalition and provincial authorities said Tuesday.
Police in the province of Kandahar said the Black Hawk helicopter came down late on Monday evening during a heavy rainstorm in Daman district, AFP reported.
The NATO-led International Security Assistance Force (ISAF) does not release the nationality of casualties, but a Western military official who declined to be named confirmed that the victims were all US forces personnel.
"The cause of the crash is under investigation. However, initial reporting indicates there was no enemy activity in the area at the time," ISAF said in a statement.
A spokesman said that all on board the helicopter had died in the crash.
A Taliban representative in Kandahar said the militants had brought down the aircraft, although the group often makes false claims of responsibility for incidents in which NATO troops die.
Helicopter crashes are fairly frequent in Afghanistan, where the 100,000-strong international mission relies heavily on air transport as it battles against the insurgency across the south of the country.
"There was bad weather in the area and the helicopter crashed at about 10:00 pm," Kandahar provincial police chief General Abdul Razeq told AFP. "No insurgents were there at the time."
Daman district is one of most stable areas of Kandahar, a province at the heart of the unrest, and local officials said the crash site was not far from Kandahar city.
Last August seven American soldiers and four Afghans died when another Black Hawk helicopter crashed in Kandahar.
Monday's crash came on the same day that two US soldiers were killed and 10 wounded in a suspected insider attack in the eastern province of Wardak by a man in an Afghan army uniform who also killed several Afghan soldiers.
The NATO mission in Afghanistan has been unsettled this week by comments from Afghan President Hamid Karzai accusing the US of colluding with the Taliban to justify the presence of foreign troops in the country.
Washington abruptly dismissed the allegations, saying the US has "spent enormous blood and treasure" in helping the Afghan people and did not support any kind of violence involving civilians.
Karzai made his comments during the first visit to Kabul by new US Defense Secretary Chuck Hagel, who vowed that the US was working to ensure a successful handover as Afghan security forces take on the battle against the Taliban.
Combat troops from the NATO mission will leave Afghanistan by the end of next year, and many fear that poorly trained Afghan soldiers will struggle to contain insurgents opposed to Karzai's government.
Hagel's visit to Afghanistan was also marred by twin suicide attacks, including one in central Kabul, while he was at a nearby US base in the city.
In August 2011, an American Chinook was shot down by the Taliban near Kabul, killing eight Afghans and 30 Americans, including 22 Navy SEALs from the unit that killed Osama bin Laden in neighbouring Pakistan earlier that year.