KABUL: A suicide car bomb exploded outside the NATO military headquarters in Kabul Saturday, killing seven Afghans in a brazen attack that raised alarm just days before landmark presidential elections.

The Taliban militia behind a soaring insurgency said it had carried out the unprecedented bombing near the headquarters of the International Security Assistance Force (ISAF) and close to an entrance to the US embassy.

The huge explosion, just metres (yards) from the ISAF gate in one of the most secure areas of the country, reinforced fears of violence around the August 20 presidential and provincial council elections.

President Hamid Karzai, in a statement condemning the blast, said the attack was intended to create fear ahead of the election but insisted that Afghans "will not be scared of such threats and will go to the voting booths".

It was the first such bombing at the base, which groups soldiers from several countries and is the headquarters of the US commander of 100,000 international troops deployed to Afghanistan to fight extremism.

"In the suicide attack today at 8:30 am by the enemies of Afghanistan in front of ISAF HQ entrance in Kabul the number of martyrs has increased to seven," an Afghan defence ministry statement said.

The ministry said earlier that 91 Afghans were wounded including a woman parliamentarian and four Afghan soldiers.

Five ISAF soldiers were wounded, though none seriously, a spokesman told AFP. He could not give their nationalities.

General Stanley McChrystal, the US commander of international troops in Afghanistan, rushed to the scene soon afterwards, an AFP reporter said.

"I have to see my men," he said, but refused to comment further.

The blast destroyed concrete barriers and brought down branches and a whole tree, with huge plumes of black smoke coming from a burning vehicle that appeared to have been the car bomb.

Also in the area, which was busy with morning rush hour traffic, are the Spanish and Italian embassies, state radio and television studios and the presidential palace.

A Taliban spokesman, Zabihullah Mujahid, said the strike was carried out by a member of the militia in a car packed with 500 kilogrammes (1,100 pounds) of explosives.

It was the first suicide attack on the city since February and the first one against the ISAF base established in the capital in 2002, the year after the Taliban regime was toppled in a US-led invasion.

A suicide car bomb struck the perimeter of a separate US base in the city on January 17, killing at least one US soldier and four Afghans.

The Taliban have said they would not directly attack polling stations on August 20 but have called on Afghans to boycott the polls and instead join their jihad, or holy war, for "independence".

Karzai's younger brother, Ahmad Wali Karzai, said on Thursday community leaders in the troubled south had persuaded grassroots Taliban leaders not to target the vote.

But there are fears that assaults or the threat of violence could see voters stay away from the elections, undermining what should be a milestone on a road to democracy.

Britain and France condemned Saturday's bombing as analysts said it showed the insurgents were able to strike where they wanted to, even at the gate of the powerful military alliance.

"Today's attack was a warning that the Taliban can attack any time," analyst Waheed Mujda told AFP.

"Afghan security forces and NATO forces I think will be not able to stop such attacks on election day," he said.

A spokesman for the United Nations Assistance Mission to Afghanistan, Adrian Edwards, said the strike highlighted that "these are among the most complex of elections anywhere".

Karzai, the election frontrunner, meanwhile put off a campaign trip to the violent southern province of Helmand because of warnings of an attack, according to participants of the planned rally.

His main rival, former foreign minister Abdullah Abdullah, took his tireless campaign to the eastern province of Nangarhar, receiving an enthusiastic welcome from around 10,000 supporters, an AFP photographer said.

And Ashraf Ghani, another frontrunner, visited the southern city of Kandahar, telling around 4,000 locals that as president he would throw a security cordon around the troubled city and install a competent government.