A Nyala vehicle is designed to resist a blast equivalent to two anti-tank mines detonating at the same time. This 2004 picture shows a Nyala and Canadian engineers. ((Cpl. Robert Bottrill/DND))

Three Canadian soldiers were slightly injured in Afghanistan when a bomb exploded near their armoured vehicle while travelling north of Kandahar on Saturday.

Two of the three are expected to return to duty after a brief rest, while the third remains under observation in hospital at Kandahar airfield, the CBC's James Cudmore said from Afghanistan on Sunday.

The military has not released the names or units of the injured soldiers, although two of them are known to be military combat engineers.

They were travelling in a Nyala armoured vehicle, which is designed to provide protection against land mines and improvised explosive devices (IEDs).

The IED blew up as the soldiers conducted a mine sweeping patrol in the Arghandab district, just north of the city of Kandahar. The attack happened in an area previously thought to be relatively secure, Cudmore said.

Canadian Forces spokesman Lt.-Cmdr. Pierre Babinsky said the insurgents have been reduced to planting bombs because of the Canadian military's success in closing down their operations.

"They have to resort to these harassment tactics," Babinsky said.

The last time a Canadian soldier was injured by an IED was on Nov. 27.

Canada has about 2,500 troops deployed in Afghanistan, as part of the NATO-led International Security Assistance Force.

It has lost 73 Canadian soldiers and one diplomat since the mission began in early 2002, shortly after the United States invaded in the wake of the Sept. 11 attacks to oust the Taliban government.