Afghan television said a would-be assassin was intercepted in Kabul when his car, loaded with explosives, was involved in a road accident.

International terrorism once again is showing its face. The enemies of Afghanistan are not sitting quietly

Official statement

The TV report, quoting a statement from the Afghan intelligence service, said that the man had planned to crash his car into a vehicle, or vehicles, carrying members of the national leadership.

It is not clear if the Afghan President Hamid Karzai was the target of the planned attack.

But the statement from the General Department of National Security said the car "should have collided with one of the vehicles carrying the leader of Afghanistan's Transitional Islamic State".

The statement added that security forces had arrested the driver who was "a subject of a foreign country".

It blamed "international terrorists... who planned a sinister operation".

The US Defense Secretary, Donald Rumsfeld, said he had not heard of the incident but he was not surprised.

He said that the Taleban, al-Qaeda and some Afghan factions had motives to attack the Afghan Government.

"We can expect that there will continue to be firefights and people shooting and things happening. It is an untidy place," Mr Rumsfeld said.

Kabul television showed pictures of police removing blocks of yellow explosives from the Toyota Corolla and said that some weapons had been seized as well.

Al-Qaeda rooted out

The report also showed a photograph of the suspect - a bearded young man in a vest and open shirt.

It did not say what nationality the driver was, although correspondents say that, in Afghanistan, the term "foreign" usually refers to Arabs or Pakistanis.

Arabs and Pakistanis made up the hard core of Osama Bin Laden's al-Qaeda network.

A second man was arrested in the case, according to Interior Ministry spokesman Alishah Paktiawal, but he gave no details.

US-led coalition forces are still trying to flush out the remnants of al-Qaeda in Afghanistan.

The killing of the vice president raised security fears

A spokesman for the International Security Assistance Force (Isaf) - the UN-mandated peacekeepers who police Kabul - told Reuters news agency that they had heard of the incident but knew no details.

Afghan authorities have not yet commented.

President Karzai caused controversy last week by asking to be protected by American bodyguards.

Mr Karzai had previously been guarded solely by Afghans, most of them mujahideen fighters.

But after the assassination of Afghan Vice President Haji Abdul Qadir earlier this month fears for the safety of Mr Karzai have grown.

A presidential spokesman said Mr Karzai still trusted his Afghan guards but felt highly-trained Americans would add to his security.

Mr Qadir was shot dead in his car in Kabul on 6 July, along with his son-in-law.

The aviation and tourism minister, Abdul Rahman, was beaten to death in February at Kabul airport. Neither murder has been solved.