KABUL, Afghanistan — Terrorists in Afghanistan, Zimbabwe and other volatile countries are targeting aid workers and other civilians, a tactical shift that heightens the risk to those delivering humanitarian assistance in some of the world's hot spots, says Canada's minister of international co-operation.

Bev Oda, whose ministry encapsulates the Canadian International Development Agency, or CIDA, was in the Afghan capital of Kabul to unveil a new memorial to Canadian civilians who have died in the battle-ravaged country.

She cited a recent rash of incidents, including attacks on humanitarian vehicles in Zimbabwe and the kidnappings of aid workers and diplomats elsewhere, as proof that insurgents are evolving in a frightening new direction -- one that hasn't been seen before in the ongoing war on terror.

"I think this whole terrorist insurgency, the way they operate, is changing and they're evolving. It's something new," Oda said.

"It's not just Afghanistan. Unfortunately, the evolution says there's a higher threat for civilians who do work in foreign countries and, particularly, hostile countries. But it hasn't, I think, diminished our determination."

The marble slab near the main entrance to the Canadian Embassy is engraved with the words of the Afghan poet, Rumi, about the earth mingling with the sky -- fitting symbolism for the relationship between civilians in the military working together in Afghanistan.

"You too must mingle my friends since the earth and the sky are mingled just for you and me," reads one verse.

The plaque honours two Canadian aid workers, Shirley Case of Williams Lake, B.C., and McGill University professor Jacqueline Kirk, who were killed last summer in a Taliban ambush along with an American-Trinidadian aid worker and their Afghan driver.

The women, who were working with the New York-based agency International Rescue Committee, were travelling to Kabul from the eastern city of Gardez when they were attacked by five gunmen armed with Kalashnikov assault rifles.

The memorial also pays tribute to Glyn Berry, the British-born Canadian diplomat killed in 2006 by a suicide bomber. The attack happened when Berry was on his way back to the NATO military base in Kandahar, where the bulk of Canada's 2,750 troops are deployed.

Aid agencies say attacks on their workers in Afghanistan are on the rise; 30 of their workers were killed in Afghanistan last year. As a result, most have largely restricted their activities to Kabul to avoid parts of the country deemed too dangerous.

"There is an increased risk to humanitarian workers here in general," said Ciaran Donnelley of the International Rescue Committee.

"The conflict has expanded geographically, but also it's intensified in terms of the tactics that are being used. There's a tendency to focus more on vulnerable targets."

Canada has seen its share of kidnappings recently, both within Afghanistan and elsewhere.

Canadian diplomat and United Nations special envoy Robert Fowler, his Canadian assistant Louis Guay and their driver have been missing since Dec. 14, when they vanished during a UN aid mission in the African country of Niger.

CBC TV reporter Mellissa Fung was snatched by gunmen near a refugee camp outside Kabul on Oct. 12, and released unharmed nearly a month later.

Beverly Giesbrecht, a Vancouver freelance journalist who converted to Islam and changed her name to Khadija Abdul Qahaar, was abducted Nov. 11 in northern Pakistan.

And Amanda Lindhout, a freelancer born in Sylvan Lake, Alta., was kidnapped in Somalia in August along with Australian photographer Nigel Brennan.

Donnelley said the insurgents in Afghanistan see non-governmental aid workers as legitimate targets because of a perceived association with NATO and U.S. forces. That limits the reach of humanitarian aid desperately needed in some parts of this impoverished country.

"There's certainly restrictions on our international staff, who mainly are restricted to Kabul these days," he said.

"We are lucky as an organization that we have a very strong Afghan team, but even they face increasing risks because of the situation."

The plaque joins thee other marble slabs from Camp Julian that are dedicated to fallen Canadian soldiers.