Askari 6 wa Marekani wafa Afghanistan

Six U.S. marines were killed in a helicopter crash in Afghanistan, American officials said today.

The crash in Helmand Province is the worst since last August when 30 soldiers, including elite U.S. Navy Seals, were killed.

The cause of the accident is unknown - although there was no enemy activity area at the time of the crash.

The Nato helicopter involved was believed to be a Marine CH-53 Sea Stallion.

The crash happened hours after seven civilians were killed in a suicide bombing outside Kandahar Air Field - a base for U.S. and Nato operations.

The Taliban claimed responsibility for the attack and said they were targeting a Nato convoy.

Two witnesses said they suspected the suicide car bomber was trying to hit U.S. forces because he detonated his explosives just as two pick-up trucks, which they say are often used by American special forces, were leaving the base.

Taliban spokesman Qari Yousef said Nato forces opened fire after the bombing and that they killed three of the seven civilians who died.

The coalition denied this, saying there was no fighting after the blast.

Earlier, officials reported that the suicide bomber was walking near the gate, but the Afghan Ministry of Interior later said the attacker was driving a Toyota Corolla.

Zalmai Ayubi, the spokesman for the Kandahar provincial governor, said two children were among the seven civilians killed