KANDAHAR, Afghanistan - The Canadian military bristled at a suggestion Monday that more than three dozen Afghan deaths and injuries to four Canadians could have been avoided if it had taken the advice of the Afghan government.

Canadian troops had been on a routine patrol along the Afghan-Pakistan border Monday afternoon when a car full of explosives detonated near their convoy.

Thirty-eight Afghans were killed, more than two dozen were wounded and four Canadians were lightly injured in the attack at Spin Boldak, about 75 kilometres south of Kandahar city.

"We told NATO six times not to come in these areas because for the last two days a suicide bomber has been circulating,'' said Asadullah Khalid, the governor of Kandahar province.

"But they continue patrolling the area. We repeatedly told them not to come out until we arrest the suicide bomber.''

But a military spokesman said the Canadian Forces make the decisions on where its soldiers will patrol.

"We regularly receive threat warnings and obviously we go where we want to, when we want to in our area of operation,'' said Lt.-Cmdr. Pierre Babinsky.

"We obviously take notice of these warnings but our aim is to operate freely within our area of operation despite those.''

Three of the four Canadian soldiers injured in the blast have been released from hospital; the fourth was expected to remain overnight Monday for observation.

One military vehicle was damaged during the explosion.

"We have to say that targeting ISAF forces in a populated area where men, women and children were killed and wounded demonstrated insurgents' total disregard for human life,'' said Babinsky.

"Out thoughts and condolences go to the people of Spin Boldak in this tragic time.''

Monday's blast followed the worst bombing Afghanistan has ever seen.

More than 100 people were killed on Sunday when a suicide bomber blew himself up at a dogfighting match outside Kandahar city.

The Taliban, which denied it carried out Sunday's attack, immediately claimed responsibility for Monday's marketplace bombing in Spin Boldak, which is only some 100 metre from the border with Pakistan.

"The attacks show that the enemies of Afghanistan are changing their tactics. Now they are not thinking about civilians at all,'' said Nasrullah Stanikzai, a professor of political science at Kabul University.

"They wanted to cause such big casualties in these attacks to weaken the morale of the government and the international community, to show the world the Afghan government is too weak to prevent them,'' he said.

Spin Boldak is one of four districts among 17 in Kandahar province where Canadians maintain a steady and strong, presence.

Soldiers there train the Afghan National Army and police, as well as work with border officials. The military recently held a medical outreach clinic in the area, which attracted hundreds of local residents.

Squadron Leader Peter Darling, a spokesman for NATO's International Security Assistance Force in southern Afghanistan, said ISAF forces provided medical assistance at the scene.

"We strongly condemn this cowardly attack on the civilian population, who were attacked by insurgents during the course of their daily business,'' Darling said.

When asked about the large number of civilian casualties, Taliban spokesman Qari Yousef Ahmadi claimed that 10 foreign soldiers and "a large number of police'' had been killed.

With files from The Associated Press