Canadian soldiers in Afghanistan may become targets in a planned wave of attacks by the Taliban.

Members of the former Afghan regime claim to have 60 to 120 suicide bombers ready to strike at peacekeeping forces and foreign aid workers in Kabul.

Various Taliban sources say the bombers have entered the Afghan capital and are planning to attack the International Security Assistance Force, or ISAF, as well as UN workers.

"A group of 200 mujahideen (holy warriors) has penetrated various Afghan cities," said Mullah Sabir Momin, Taliban deputy operational commander in southern Afghanistan.

"In Kabul alone, 130 trained Taliban are present on suicide missions."

CTV's Matt McClure says Canadian military officials are taking the threat of more suicide bombings seriously.

"Certainly here at the main Canadian base there's a heightened level of security today. They're taking this very seriously," he reports.

Maj. Greg Smith, the operations officer for the Canadian Forces battle group in Kabul, says the military takes all threats seriously. But he adds Canadian soldiers are ready for anything, and they're not getting "nervous about it."

The threats come one day after a suicide bomber killed four Afghan security officers, their driver and himself. Police blame the Taliban or al Qaeda for the attack.

The suspect detonated explosives hidden under his clothing moments after the agents had arrested him and bundled him into a sports utility vehicle near the airport, the Kabul police chief said.

Remnants of the Taliban claimed responsibility on Monday for the attack and vowed to launch a fresh wave of violence aimed at cities.

The bombing was the latest in a series of violent incidents since delegates from around the country began meeting in Kabul to draft a new constitution for Afghanistan. The U.S. military has warned that Taliban insurgents and their allies want to disrupt the gathering.

More than 400 people have been killed in guerrilla attacks since early August. But until now, the deadliest attacks have been in remote areas of the south and east.

In October, two Canadian soldiers, Sgt. Robert Short and Corp. Robbie Beerenfenger, were killed when their unarmoured vehicle hit a landmine as they conducted a routine patrol outside Kabul.

There are almost 2,000 Canadian soldiers working as part of the ISAF force in and around Kabul, providing stability and security for Afghanistan's civilian government. They are scheduled to return to Canada after the summer.