Canadian soldiers have joined the largest coalition effort thus far to root out hundreds of suspected Taliban fighters, focusing on a key insurgent stronghold in southern Afghanistan.

The operation is the largest to date in "Operation Mountain Thrust," and involves about 5,000 U.S., British and Canadian troops.

The aim is to attack about 400 Taliban guerrillas believed to be operating in the Sangin district of Helmand province, west of Kandahar.

CTV's Steve Chao said the Sangin area is a challenging war zone. There are many mud-walled buildings in maze-like communities, which have to be searched with caution.

"They have to be very careful about the civilian population," Chao told CTV Newsnet. "There was a great deal of concern that the Taliban would be using people as human shields, though there's no word that this is happening so far."

Chao, who was out with Canadian soldiers during a 60-hour firefight near Pashmul last weekend, said one officer told him that fighting the Taliban is "like punching flies -- you punch them and they come back again."

Sangin is the area where a Canadian soldier was killed last March.

Canadian coalition spokesman Major Scott Lundy told The Canadian Press that 10 Taliban have been killed in a brief battle, as this weekend's operation continues.

The joint Canadian-American-British mission is also the largest combat operation of its kind since the Korean War. It's led by Brig. Gen. David Fraser, a Canadian who is commander of coalition forces in southern Afghanistan.

About 600 Canadian soldiers are assigned to the operation, and Chao says they've been fighting in 50 degree Celcius heat in recent months. Many are exhausted and are counting the days until they can go home.

Rocket hits coalition base, no reported casualties

Meanwhile, another rocket struck the coalition base in Kandahar, where Canadian troops are based.

The rocket hit the base Saturday, though there were no reported casualties.

It is one of about 30 rockets that have struck the base in the past few months, said Chao, reporting from the scene.

"At least one rocket landed on the Kandar airbase. We outrselves could hear the whistle of the rocket as it flew over our heads and landed just a few hundred metres from where we are," Chao told CTV Newsnet.

"We could see a cloud of smoke and dust rise up from where the rocket landed. We ourselves ran over to the site but we were told no one has been injured in the attack."

Chao said the numerous attacks in recent months are difficult to guard against.

"There are so many areas the Taliban or insurgents can fire the rockets from, so it's just another example of how difficult it is to police the outside cordoned area."

He said the base covers several square kilometres.

The attack marks the second time in one week that the base has been targeted. It is the fifth such attack since June 30 when two Canadians were injured by rockets.

With files from CTV's Steve Chao in Kandahar and The Canadian Press