LONDON —  Canada is an emerging "energy superpower" that's the most attractive investment opportunity in the world, Prime Minister Stephen Harper told a London business audience Friday.

On the eve of a G8 conference in St. Petersburg, Harper used his address to the Canada-U.K. Chamber of Commerce to establish Canada's bona fides on the oil and gas front.

Energy security is supposed to be one of the key themes as Russia, for the first time, plays host to the Group of Eight industrialized countries over the next three days.

Russia and Canada are the only two net energy exporters among the G8, and Harper appeared determined to ensure Canada's voice is heard at the table among such heavyweights as the United States, Germany, France and Britain.

British investors, Harper told his well-heeled audience in London, "have recognized the emergence of Canada's global energy powerhouse. Or as we put it, the emerging energy superpower our government intends to build."

"This is no exaggeration."

As evidence, Harper said Canada is the world's third largest producer of gas, seventh in oil production, the biggest hydro-electric generator and the biggest supplier of uranium. Alberta's tar sands are second only to Saudi Arabia as the world's largest oil reserve.

And in a thinly veiled shot at his G8 host, Harper said Canada believes in "a free exchange of energy products based on a competitive market - not self-serving monopolistic political strategies."

Russian President Vladimir Putin has drawn sharp criticism from around the western world for his government's heavy-handed state control of the country's vast oil and gas reserves and their distribution network.

In January, Russia briefly cut gas supplies to the Ukraine in a dispute it said was over pricing, but others believe was bare-knuckle politicking.

In an effort to overcome the criticisms in advance of the G8, the Russian government hired a Washington-based communications firm to help buff its image.

Igor Shuvalov, Putin's G8 ambassador, was offered up to western journalists, and made a spirited pitch for foreign investment and technology transfers in the energy sector.

"We are talking only about market-based mechanisms," Shuvalov told The Canadian Press.

"The state's role first of all is to provide stable and transparent framework for investors. And to act only where the private sector cannot act."

Skeptics point to the Russian government's takeover of energy giant Yukos, and the imprisonment of former Yukos billionaire Mikhail Khodorkovsky in Siberia.

One human rights commentator has called Russia "a one-pipeline state" as opposed to its former one-party status.

Harper is clearly vying with Putin for energy investment dollars, and he pointedly quoted unnamed market analysts Friday as saying that Canada has "the most attractive combination of circumstances for energy investment of any place in the world."

All this sets up a lively bilateral meeting Saturday afternoon between Harper and Putin after the Canadian delegation arrives in St. Petersburg from London.

As if to prime the pump, the inflight movie shown on Harper's Canadian Forces Airbus flying to Europe this week was Syriana - George Clooney's political thriller about American oil interests, in cahoots with the U.S. government, subverting emerging democracies in pursuit of energy monopolies.