KABUL, June 7 (IslamOnline.net & News Agencies) - Four German soldiers were killed and 29 were injured in a bomb attack on a bus carrying members of the International Security Assistance Force (ISAF) in Afghanistan early on Saturday, June 7, German Defense Minister Peter Struck announced in Berlin.

Afghan military officials said six people died in all, including one or two bombers in a taxi that exploded as it drew alongside the bus.

ISAF said in a statement earlier in the day that three German soldiers had died in the apparent “suicide” attack, the deadliest to date against ISAF, reported Agence France-Presse (AFP).

"This attack has a new and horrible dimension," said the German minister.

He said German criminal police would be traveling to Kabul shortly to investigate the blast, which threw the bus some 10 meters off the road and completely destroyed the taxi.

But Struck said there were no indications to date to suggest the attack was the work of al-Qaeda.

He also rebuffed suggestions that the peacekeepers had been careless to travel in a non-armored vehicle.

The bus was traveling along the main road linking Kabul to the eastern city of Jalalabad, which is used daily by dozens of ISAF vehicles.

"I don't think we acted imprudently," he said, rejecting calls by the head of the German army union, Bernhard Gertz, for German troops to be pulled out of the troubled Central Asian country.

Seven of the Germans injured were in serious condition and were to be flown out urgently to Germany, Struck told a news conference in Berlin.

The attack was the latest in a series of incidents to blight the peacekeeping force, which has patrolled Kabul under a United Nations mandate since the ouster of Taliban in late 2001.

It was the second violent incident involving German peacekeepers in Kabul in recent weeks.

Germany contributes 2,300 soldiers to ISAF, its largest national contingent, and currently shares command of the 4,700-strong force with The Netherlands.

U.S. President George W. Bush telephoned German Chancellor Gerhard Schroeder from his Camp David retreat Saturday "to express his condolences for the deaths of German soldiers during an attack in Afghanistan," the White House said.

"The president and Chancellor Schroeder reinforced their determination to continue to combat terrorism," White House spokeswoman Jeanie Mamo added in a telephone conference call with reporters.

A French foreign ministry spokesman said that "in hitting at the international force that is in Afghanistan in the name of the United Nations, this terrorist act seeks to derail the process of peace and reconciliation."

The attack "should strengthen our shared determination to see through this process and to oppose all forms of violence," Francois Rivasseau said.

The bombing was also denounced by Afghanistan’s neighbor Pakistan.

"Pakistan strongly condemns the reprehensible and cowardly act," foreign ministry spokesman Aziz Ahmed Khan told AFP, offering his condolences to the victims' families.