Al-Qaeda has included Canada in a list of countries that it believes should be attacked for providing oil to the United States.

The Saudi Arabian arm of the network posted the threat on Sawt al-Jihad (Voice of Jihad), the group's online magazine, according to the Search for International Terrorist Entities (SITE), a U.S. non-profit group that monitors militant websites.

The website is known to be used by Islamist militants.

The threat, written as an article, encourages the mujahedeen to continue to follow Osama bin Laden’s directives and strike oil targets not only in Saudi Arabia, but elsewhere, including in Mexico and Venezuela, SITE said. Those targets include oilfields, pipelines, loading platforms and carriers.

"We should strike petroleum interests in all areas which supply the United States, and not only in the Middle East, because the target is to stop its imports or decrease it by all means," it states.

The militant group launched an unsuccessful suicide bomb attack at the world's largest oil-processing facility, the Abqaiq oil facility in Saudi Arabia, last February.

Attackers had two cars packed with explosives and were trying to ram the gates when guards opened fire. The cars exploded, killing the attackers.

According to the latest figures, Canada remains the top supplier of oil to the U.S., followed by Mexico and Saudi Arabia. Despite the tense relations between Washington and Caracas, Venezuela is listed as fourth on the top list of suppliers.

Alberta Premier Ed Stelmach said security experts are well aware of the threat.

He said the Energy and Utilities Board is monitoring the situation, but that the threat has not alarmed security agencies and he's confident Albertans should not be overly worried.

"All I can say is I feel secure as an Albertan and so should all Albertans. There will be threats ongoing, given the issues, especially in the Middle East," he said.

But Martin Rudner, who heads the Canadian Centre of Intelligence and Security Studies at Carleton University, said the threat is "very serious" and the group is motivated to strike.

Rudner said the warning appeared as part of the Voice of Jihad's internal magazine and that it wasn't intended for foreign readers, but for their own operatives.

He said the article includes a detailed review of their attack on the Abqaiq refinery and was intended to guide them for their next operations elsewhere in the world.

"And elsewhere in the world they target, in fact, suppliers of oil to the United States and they single out Canada."

Greg Stringham, vice-president of the Canadian Association of Petroleum Producers, told CanWest News that they too are taking the threat seriously.

"It's not the first time that it's happened and we have no credible threat to substantiate it, but still, we are taking it seriously and we've informed all of our members and contacts about that — especially those with critical infrastructure — to pay extra attention and be vigilant."