KABUL, Afghanistan -- A helicopter carrying NATO forces crashed in a western Afghan desert yesterday, and another helicopter with it made an emergency landing. Seventeen Spanish troops were killed and five were injured, while providing security ahead of legislative elections.
There were conflicting reports about what had caused the crash, the biggest loss of life for NATO forces in Afghanistan. A spokesman for NATO's International Security Assistance Force said the crash and emergency landing in Herat province were believed to be accidents, but Spain's defense minister, Jose Bono, said he did not rule out hostile fire.
''It could have been an accident or it could have been an attack," Bono said in Madrid.
The Afghan president, Hamid Karzai, said the crash had been caused by a sandstorm.
However, the Afghan army commander, Abdul Wahab Walizada, whose troops provided security at the site, said the weather was fine. He said that the helicopters had been flying too close, , and rotor blades of one had clipped the other.
One helicopter burned; the other was damaged severely, Walizada said.
The 17 dead, 12 soldiers and five crew members, were on the helicopter that crashed, said Major Andrew Elmes, a spokesman for the International Security Assistance Force. The five injured were on the second aircraft, which made a ''hard landing," he said. They were in stable condition at a hospital in Herat.
Twelve other soldiers on the second chopper were not injured.
In Washington, a Pentagon spokesman, Bryan Whitman, said preliminary information had shown no indication that the aircraft had been shot down or had collided with another craft.
Bono said the two Spanish Cougar AS532 helicopters were flying together at the time. One pilot reported seeing a column of black smoke in a nearby valley, flew closer to the spot, concluded it might signal an attack from the ground, and decided to make an emergency landing.
The other helicopter crashed, Bono said.
He also said that Spanish officials initially believed the crash was probably an accident, but they later saw a photo showing that the area where the helicopter crashed was level, making it conducive to an emergency landing.
That ''leads the military high command not to rule out the hypothesis that it could be an attack rather than an accident," he said.
The Spanish prime minister, Jose Luis Rodriguez Zapatero, who broke off his vacation in the Canary Islands to return to Madrid, praised the 17 soldiers.
''They honored a pledge to defend freedom and peace -- supreme values that Spaniards are very committed to," he said.
Secretary of State Condoleezza Rice called Spain's foreign minister, Miguel Angel Moratinos, to express her condolences, a State Department spokesman, Sean McCormack, said in Washington.
The victims were the first Spanish troops to have been killed in Afghanistan, officials said. Spain has about 800 troops in Afghanistan who are assisting the NATO force.
That 10,000-member force is in the country ahead of Sept. 18 elections. Elmes said both choppers were on a training mission to support the vote -- the next key step in the country's path to democracy after two decades of war.
Rebels linked to the Taliban have stepped up attacks in the past six months, and have vowed to sabotage the polls. But they have focused their activities in the east and south, rarely striking in Herat and other western areas, where the helicopters crashed.
NATO plans to take over from the 17,000-member US-led coalition hunting Taliban and Al Qaeda rebels in the south early next year, before the force moves into the east.
The crash was the second major deadly event involving Spanish troops deployed in Afghanistan. In May 2003, 62 Spanish soldiers returning home from Afghanistan were killed when their Russian-built YAK-42 plane crashed near Trabzon, in northwestern Turkey. Thirteen Ukrainian and Belarusian crew members of the aircraft also died.