|More than 2,000 Nato troops have died since the US-led invasion of Afghanistan in 2001 [EPA]
At least one person has been killed in an explosion inside a US helicopter shortly after it landed at a military outpost in eastern Afghanistan, military officials said.
Seven troops from the Nato-led security force in Afghanistan were also wounded on Tuesday, in an attack for which the Taliban has claimed responsibility.
The US-led International Security Assistance Force (Isaf) said in a statement that the cause of the explosion was unclear and that 26 people had been on board the aircraft.
Isaf initially announced that 10 troops were wounded in the incident and two people were killed, but a spokesman later revised the casualty figures.
"Operational reporting is very fluid. You've got to understand that we're trying to get all the facts," the spokesman told the AFP news agency.
"There are seven wounded and one killed in action. It is up to respective governments to release the killed in action. The seven wounded are Isaf personnel."
Another Isaf spokesman identified the aircraft as a US-made Chinook, and said that the landing site had been secured by Afghan and Nato soldiers.
Eastern Afghanistan is one of the most volatile parts of the country, where the Taliban and other anti-government groups have a strong presence.
The attack comes after roadside bombs killed at least seven people including two Nato troops on Sunday.
Elsewhere, five members of a family died in a roadside blast in eastern Paktia province, while Nato troops were killed in an explosion on a highway in southern Afghanistan, the military alliance said.
Sunday's deaths, which have brought to 26 the number of Nato forces killed this month, came a day after four Italian troops died in a roadside blast in western Farah province.
There are currently around 152,000 foreign troops under US and Nato command in Afghanistan, and
two-thirds of the troops are American.
At least 2,014 Nato troops have died since the US-led invasion of Afghanistan on October 7, 2001, according to an Associated Press count.