OTTAWA — The government's plan to re-equip the Canadian army in Afghanistan with modern Leopard 2 A6M tanks was greeted with skepticism by experts who question whether the iron monsters will counter roadside explosives and suicide bombers.

"In the short term, it may provide a measure of additional protection -- but no armour is impenetrable,'' said Steve Staples of the Ottawa-based Rideau Institute, an international affairs think-tank.

With the army in its bloodiest week of fighting since the Korean War, Defence Minister Gordon O'Connor emphasized the added protection the heavy vehicles will afford when he announced the procurement Thursday.

"We feel it's best for our troops that we acquire stronger, heavily armoured main battle tanks that offer increased protection,'' O'Connor said following a meeting in Quebec with some of his NATO counterparts.

"These tanks have proven to be truly effective. This government has not and will not hesitate to provide the Canadian Forces with the heavy protection they need to do the very demanding jobs we've asked of them.''

The deeper Canada has gone into the Afghan war, the more it has been forced to break out the heavy equipment, he said.

The army replaced its aging Ilitis jeeps with G-Wagons, only to turn around and sideline them with blast-resistant RG-31 Nyalas as insurgent bombs grew more powerful.

Last fall, an older version of the Leopard tanks, which are tracked vehicles, were introduced as the wheeled LAV IIIs and Bison armoured personnel carriers became stuck in the deeply rutted grape fields of west of Kandahar.

The powerful Easter Sunday explosion, which wrecked a LAV III and killed six soldiers, is proof that the Taliban are adapting and could very well build a powerful enough bomb to knock out a tank, said Staples.

"Israeli tanks in Lebanon and American battle tanks in Iraq, which are actually even heavier than the Leopard 2s, have been defeated by insurgent tactics,'' he said.

A U.S. expert in counter-insurgency warfare said the decision to swap out the older Leopard tanks with new ones was wise, but should not be portrayed as a solution to rising casualties.

"You are fighting an adaptive enemy who learns as you learn,'' said Anthony Cordesman, at the Washington-based Center for Strategic and International Studies.

"There is no one tool out there that can halt an insurgency. They'll always find countermeasures. You'll have to find counter-countermeasures.''

Up to 20 Leopard 2 battle tanks will be borrowed from Germany, modified with extra floor plating and blast-resistant seats, then shipped to Kandahar this summer to replace Canada's geriatric Leopard 1 vehicles.

At the same time, the Defence Department will purchase 100 slightly used Leopard 2 tanks, which have been carefully mothballed, from the Dutch.

The tanks Canada is purchasing can travel twice as fast in difficult terrain as the existing ones which, apart from being 30 years old, are ill-suited to operate in the stifling Afghan summer heat.

None of 17 armoured vehicles currently fighting in NATO's Operation Achilles have air conditioning, a source of worry for tank crews who were likely going to face summer temperatures of 60 degrees Celsius inside the tank compartment.

O'Connor said the new tanks have more crew comforts and will be equipped with air conditioning.

The purchase is a change of direction for the army and in particular for Chief of Defence Staff Gen. Rick Hillier, who only a few years ago described the Leopard tanks as "millstone around the neck'' of the forces.

The Defence Department toyed with the idea of replacing the heavily tracked tanks with a wheeled, unproven mobile gun system called a Stryker.

"Ideally, we wanted a smaller, lighter vehicle that had smaller crews,'' Hillier told the Quebec news conference where the new tanks were announced.

"Something that could perhaps manoeuvre better on some of the smaller trails and some of the tinier villages where we were. The mobile gun system appeared to offer that, but it does not.''