A car bomber attacked a Nato convoy in the Afghan capital yesterday, killing at least 15 people and wounding more than 30, officials said.

The suicide bomber attacked the convoy in the east of Kabul with a car packed with explosives, a Kabul provincial police spokesman said.

"The explosion was very big. It set the nearby buildings on fire," he added. "The casualty numbers are high and mostly civilian."

Kabul deputy police chief Daud Amin said it was difficult to immediately estimate the number of dead. He said: "We saw two dead bodies of children on the ground."

Two Kabul hospitals reported at least 15 dead and 37 wounded were admitted.

A Muslim militant group, Hizb-e-Islami, claimed responsibility for the early-morning attack.

A spokesman said one of its operatives carried out the attack on what he described as two vehicles of US advisers.

He claimed most of the American advisers were killed and their vehicles destroyed but it later emerged that at least two Americans were among the fatalities.

Hizb-e-Islami is headed by 65-year-old former warlord Gubuddin Hekmatyar, a former Afghan prime minister and one-time US ally who is now listed as a terrorist by Washington.

The militia has thousands of fighters.

Yesterday's attack was the second in eight months claimed by Hizb-e-Islami.

In September, the militant group claimed a suicide car bombing that killed least 12 people.

Hizb-e-Islami said the attack was revenge for the film Innocence Of Muslims, which was made by an Egyptian-born US citizen and infuriated Muslims for its negative depiction of the Prophet Mohammed.