KABUL: The Taliban said they detonated a bomb on a fuel tanker Wednesday and then opened fire on other Nato  supply trucks in a morning attack that destroyed 22 vehicles loaded with fuel and other goods for US-led coalition forces in Afghanistan.  

In western Afghanistan, a Nato helicopter crashed, injuring two troops serving with the US-led military coalition, Nato said.

The helicopter went down early Wednesday at an undisclosed location in the relatively peaceful west. No other information has been released about the crash, which is under investigation.

The Taliban said they attacked Nato supply trucks parked overnight in Samangan province in the north.

''We put explosives on a fuel tanker. When it exploded, we fired on the trucks,'' Taliban spokesman Zabiullah Mujahid told The Associated Press in a telephone call.

Sidiq Azizi, a spokesman for the province, said many tankers and semi-trailers caught fire after the bomb went off around 2 a.m.

By mid-day, heavy black smoke still poured from the Rabatak area of the province where the truckers had stopped to rest. Firefighters were spraying water on the burning vehicles.

''There was a big boom,'' Azizi said.

''It's possible that is was a magnetic bomb from insurgents. We are investigating.''

''I counted 20 fuel tankers burning. There is still a very big fire,'' said Azizi, who was at the scene. ''The weather is very hot and it's hard to get close to the fire.''

The tankers in the convoy were transporting fuel south toward the Afghan capital, Kabul, from neighboring Uzbekistan to the north.

Earlier this week, three Nato supply trucks were destroyed by militants in Sayd Abad district of Wardak province in eastern Afghanistan.    Convoy traffic in the east has gotten heavier since Pakistan reopened its border crossings about two weeks ago.

Islamabad blocked Nato supply trucks for seven months in retaliation for US airstrikes that killed 24 Pakistani soldiers.

Separately, Nato reported that two coalition troops have been killed, one Tuesday during an insurgent attack in the south and another on Wednesday in a roadside bombing in the east.    The troops' nationalities have not yet been released.

So far this year, 239 coalition service members have been killed in Afghanistan, including at least 172 Americans.