EDMONTON - While the oilsands industry tries to calm any frayed nerves after a splashy protest by Greenpeace at a Shell work site in northern Alberta, some analysts say the infiltration of such a huge operation should serve as a warning about the security of energy installations.

If demonstrators can get into the site, so could terrorists intent on doing real damage, says Tom Flanagan, a University of Calgary political science professor and author of a report about groups opposed to development of Western Canada's resource sector.

"It does raise concerns," Flanagan says. "It would be wise to take this as a warning of the importance of reviewing procedures to make sure this kind of thing couldn't happen again."

About two dozen protesters from Canada, the United States and France gained access to Shell's (NYSE:RDS.D) Muskeg River mine site north of Fort McMurray, Alta., last Tuesday, chaining themselves to giant dump trucks and a four-storey-tall shovel that scoops oily sand from the bottom of a massive pit.

After unfurling a banner which read, "Tarsands: Climate Crime" and spending 31 hours at the mine, the protesters left the fenced and gated site without any charges laid.

Fred Lindsay, Alberta's solicitor general and minister of public security, says he'd also like to know how the Greenpeace protesters gained access to the tightly controlled site.

But he notes that Alberta's energy infrastructure is spread over a vast area and not all incidents can be prevented.

"You look at the amount of infrastructure we have in this province, the large resource developments and the miles and miles of pipeline - obviously we can't fence it all in," Lindsay says.

"This particular case with Greenpeace has turned out to be a publicity stunt but nonetheless, they gained access which created safety concerns for them as well as the site. So we're going to mark that to see what we can do to make those sites more secure."

The province watches for any possible terrorist threats and has counter-terrorism protocols in place.

Canada has a stable political climate and has few violent incidents directed at the resource sector. Lindsay doesn't expect this latest incident will affect the country's reputation as a secure supplier of energy.

Toronto-based security analyst Mercedes Stephenson says the Greenpeace action likely took time to plan and noted that the group specializes in such actions.

"I was surprised they got into the facility... but it's Greenpeace," Stephenson says. "It has a history of being able to get into all kinds of places that nobody expects them to be able to."

Oilsands operations likely wouldn't be the first target of terrorists determined to halt the flow of oil or gas from Alberta, she says.

It's more likely those groups would choose a vulnerable area along the thousands of kilometres of pipelines that snake across the province.

In recent months pipelines in northeastern British Columbia owned by EnCana Corp. (TSX:ECA) have been the target of explosions and police have yet to make any arrests.

"If somebody really wanted to do damage, they probably wouldn't go to an oilsands mining facility," Stephenson says. "You'd be far more effective if you actually disrupted the flow. Because the flow is what supplying energy."

Alberta's oilsands currently produce about 1.2 million barrels per day and the United States has called the Canadian oilsands "critically important" to energy security in North America.

Shell hasn't determined where the Greenpeace protesters gained access to the mine.

Paul Hagel, a spokesman for Shell Canada, says the incident has prompted a full-scale security review which includes its adjacent Albian Sands site.

"We're talking about 155,000 barrel a day operation and so obviously, to ensure the future security of it is paramount," Hagel says.

Hagel calls this latest incident a "blip," but added Shell will learn from it.

"These sorts of events call for wild speculation. People get the what ifs: 'What if this happened, what if that happened.' Our oilsands operation is safe and secure and I would challenge anyone who would say otherwise."

Cheryl Robb, a spokeswoman with Syncrude, which operates two oilsands mines in the same region about 450 kilometres north of Edmonton, says the company has stepped up security in the wake of the Greenpeace action.

The incident has also renewed Syncrude's efforts to seek a court injunction that would prevent Greenpeace activists from coming near company property. In July 2008, Greenpeace protesters gained access to Syncrude's Aurora mine site, netting each of them a fine for trespassing.

Mike Hudema, a Greenpeace activist who took part in the latest action, refused to discuss how the protesters gained access to the Shell site.

This latest incident doesn't change Canada's international reputation as a reliable supplier, said Greg Stringham, a spokesman with the Canadian Association of Petroleum Producers, based in Calgary.

Between conventional production and oilsands mining, there's quite a lot of diversity in how Canada supplies oil to the North American market, he said. About half of all oil production in Canada comes from the oilsands, he said.

That diversity is partly what ensures that energy supplies are secure. If an incident does occur at a specific site, there are always other production facilities and other pipelines or storage facilities that can ensure the delivery of oil to market, Stringham said.

"The individual site access is something that companies will deal with, but the overall reliability of Canada as a friendly and reliable supplier of energy I don't think has changed because of an event like this."