A purported Taliban spokesman, Qari Mohammed Yousaf, called The Associated Press and claimed responsibility for Sunday's bombing, warning 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.
There have been about 25 suicide bombings in the past four months in Afghanistan - a relatively new tactic for fighters in Afghanistan and one that has reinforced fears that this country may see more assaults modelled on those in Iraq.
Sunday's attack occurred as the convoy was driving near the Canadian base in Kandahar city, a former Taliban stronghold, said Interior Ministry spokesman Dad Mohammed Rasa. At least two civilians were killed and 10 were wounded, he said.
Lieutenant-General Marc Dumais, Canada's deputy chief of defence, said Glyn Berry, a senior foreign affairs officer and the political director of a reconstruction team in Afghanistan, was killed.
He said three of the 13 wounded are Canadian soldiers and that two are in critical condition.
Paul Martin, the Canadian prime minister, called the attack a "tragic incident" and expressed his condolences to the families of the victims.
Nine Canadians have died in Afghanistan. Four soldiers were mistakenly bombed by a US fighter pilot in 2002 and four others have died in accidents.
The Canadian prime minister said his country's mission in Afghanistan is vital.
Human bombings have become a
familiar insurgent tactic of late
"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 in Kandahar to 2,000 next month.
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 1600 people dead, the most since US-led forces ousted the Taliban in 2001 for hosting Osama bin Ladin.
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.
Hamid Karzai, the Afghan president, said in an interview with AP last week that he expects suicide attacks to continue "for a long time", though he said it was not clear whether the Taliban or other insurgent groups were behind them.