A suspected suicide car bomber blew up a bus carrying German peacekeepers in the Afghan capital Kabul yesterday, killing four soldiers and wounding 29, seven of them seriously, officials said.

The troops were on their way to the airport to fly back to Germany after completing their Afghan assignments. The attack, hours before President Hamid Karzai returned to Kabul from a foreign trip, was condemned by German Chancellor Gerhard Schroeder as a "cowardly and devious" act aimed at undermining the fragile peace in the war-torn country.

Karzai described the worst strike against the 5,000-strong International Security Assistance Force (ISAF) since its deployment in Kabul 18 months ago as a "terrorist attack". Witnesses at the scene of the blast said they saw the mangled wreckage of the car carrying the explosives and bloodstains and shards of glass on the road. The charred shell of the bus stood on the side of the road where the force of the explosion left it. It was later removed by cranes.

German Defence Minister Peter Struck's injury count of 29 did not include Afghan passers-by, also believed to have been wounded and possibly killed. The incident was the latest in a string of attacks in Afghanistan aimed at US-led coalition forces, international peacekeepers and aid agencies. At least 18 peacekeepers have died in Afghanistan, mostly in non-hostile acts.

Yesterday's explosion was the second violent incident involving German peacekeepers in Kabul in the past two weeks. A German soldier was killed on May 29 and another wounded when their vehicle hit a landmine near Kabul. Officials blamed the incident on an old mine rather than an act of sabotage.

Late last month, 62 Spanish peacekeepers returning from Afghanistan were among 75 people killed when their charter plane crashed in Turkey. ISAF has been based in Kabul since Karzai's government took over in late 2001 after US-led forces toppled the Taliban.

Karzai, who returned to Afghanistan from a trip to Britain just hours after the attack, told an audience in Oxford late on Friday that Afghanistan would be "in hell" if ISAF left the country, underlining the lack of security. Schroeder said the attack was aimed at undermining peace efforts by bombing the country back into anarchy. People in Kabul also condemned the attack.

"These people have come to keep the peace," said Mohammad Deen, speaking close to the site of the attack. They have not harmed anyone, nor have they been dishonest to anyone. Those who have done this have made a big mistake. This is very unjust that they killed them."

On Friday, a Taliban commander said the group's leader, Mullah Mohammad Omar, had ordered his forces to regroup and take revenge for the killing of his fighters in a battle this week. Afghan officials said up to 40 Taliban fighters died in a battle on Wednesday in what they described as the Taliban's biggest defeat since late 2001. About 11,500 foreign troops are in Afghanistan searching for remnants of the Taliban and al Qaeda.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.