An Afghan police officer is seen at a checkpoint in Kabul on Sunday. (Rafiq Maqbool/Associated Press)

Just days after insurgents shot and killed two Canadian aid workers in eastern Afghanistan, the Taliban is warning similar attacks will occur.

The extremist group issued the warning in a letter posted on the internet, and the CBC confirmed its authenticity on Sunday after talking to Taliban spokesman Zabiullah Mujahid in Kandahar province.

The letter said Canadians should pressure their government to withdraw Canada's troops from Afghanistan and follow a neutral policy regarding Afghanistan or "the Afghans will be obliged to killed your nationals."

"Events such as Logar will happen again," the letter said, referring to an ambush on Aug. 13 that killed Canadian aid workers Jacqueline Kirk of Montreal and Shirley Case of Williams Lake, B.C., along with Trinidadian-American aid worker Nicole Dial and the group's Afghan driver, Mohammad Aimal.

"The Afghans did not go to Canada to kill Canadians. Rather it is the Canadians who came to Afghanistan to kill and torture the Afghans to please the fascist regime of America," the letter said.

A spokesperson for Prime Minister Stephen Harper said Sunday the threat toward Canadians is nothing more than a propaganda exercise and that it won't affect the government's policy on Afghanistan.

Most of the 23 aid workers killed in Afghanistan in the first eight months of 2008 were Afghans, although the attack on workers with the International Rescue Commission last week was the worst single attack on foreigners in several years.

Insurgents most often rely on roadside bombs to target foreign forces and those seen to support their presence.

On Saturday night, a roadside explosion killed 10 Afghan police officers in the Shah Wali Kot district of Kandahar province. The region's police chief, Mutillah Khan, blamed the deadly bombing on Taliban militants.

About 650 Afghan security forces have been killed in roadside bomb blasts and other attacks in the last five months, according to the Afghan interior ministry.