A homicide car bomb hit a Canadian military convoy Sunday in southern Afghanistan, killing three civilians, including a Canadian diplomat, officials said.

A purported Taliban spokesman, Qari Mohammed Yousaf, claimed responsibility for the attack, which also wounded three Canadian soldiers and 10 other people.

He warned that "these attacks will continue for a long time. We have many more suicide attackers ready to go."

"We will continue this strategy until all foreign forces leave Afghanistan," he said in a telephone call to The Associated Press.

Afghanistan has been hit by about 25 homicide bombings in the past four months — a relatively new tactic for militants here and one that has reinforced fears the country may see more assaults modeled on those in Iraq.

Sunday's attack occurred as the convoy was driving near the Canadian base in Kandahar, a former Taliban stronghold, said Interior Ministry spokesman Dad Mohammed Rasa. At least two civilians were killed and 10 were wounded, he said.

Glyn Berry, a 59-year-old senior diplomat with Canada's Foreign Affairs and the political director of a reconstruction team in Afghanistan, also died.

Canada's Deputy Chief of Defense, Lt. General Marc Dumais, said three Canadian soldiers also were wounded and two were in critical condition with life threatening injuries.

"They had no indication that the attack was coming. It was very sudden," Dumais said.

Nine Canadians have died in Afghanistan. Four soldiers were mistakenly bombed by a U.S. fighter pilot in 2002 and four others have died in accidents.

Canadian Prime Minister Paul Martin expressed condolences to the victims' families while campaigning in Quebec and said the mission in Afghanistan is vital.

"Our participation in the mission in Kandahar is essential to establishing peace and security," Martin said. "It's in a nation that's struggling to find its way."

Canada has about 650 troops in Afghanistan, nearly all in Kandahar, and Ottawa plans to increase the Canadian military presence there to 2,000 next month as part of NATO's plans to expand its peacekeeping mission into the more volatile southern region.

A witness to the attack, shopkeeper Rahim Gul, said he saw a sedan vehicle blow up as it was passing the convoy.

"The explosion was so big. It destroyed one jeep and blew it totally to the other side of the road," he said, adding that he saw at least three wounded soldiers.

Violence across southern and eastern Afghanistan spiked last year, leaving about 1,600 people dead, the most since U.S.-led forces ousted the Taliban in 2001 for hosting Usama bin Laden.

The fighting normally eases during the winter months, when snow blankets the region, but the past few weeks have seen a string of suicide attacks and other assaults.

President Hamid Karzai said in an interview with AP last week that he expects suicide attacks to continue "for a long time," though it was not clear whether the Taliban or other militant groups were behind them.