A Taliban suicide bomber has targeted a UK embassy car in Kabul, killing a British and an Afghan diplomat and three Afghan civilians.

The explosion left at least 33 others wounded.

"A British embassy vehicle was attacked. We are working with Afghan authorities," an embassy spokesperson told news agency AFP, but refused to give further comments.

Interior minister General Ayoub Salangi initially said that the suicide bomber triggered the blast after attacking the car via motorcycle.

However, it later said that the assailant was travelling by car.

A Western security source told Reuters that one of the British employees travelling in the vehicle had died in hospital, while a second Briton was wounded and is in stable condition.

A witness saw at least one survivor being led away from the charred shell of the vehicle on foot by a member of the British security force.

The Taliban said they were behind the attack in a message on a recognised Twitter account, claiming that many foreigners had been killed.

In a statement UK's Foreign Secretary Philip Hammond praised "the courage and perseverance of the people of Afghanistan and members of the international community who support them, who have lived together through decades of conflict."

He added: "We will not allow such inhumanity to deter us from continuing our partnership with the government of Afghanistan. I have nothing but admiration for the staff of the Embassy, British and Afghan, who work at great personal risk to help build a better future for Afghanistan."

The incident occurred two days after two bomb blasts, one targeting a military bus and the other the city's diplomatic quarter, hit Kabul. No casualties were reported.

The Taliban have increased their attacks in the country as foreign troops prepare to pull out of the country next month, after 13 years of fighting.