OTTAWA - Facing sustained attack in the Commons for his government's decision to withdraw Canada from the Kyoto Protocol on global warming, Prime Minister Stephen Harper has fired back at critics.

"What made absolutely no sense for this country was a Liberal government that signed the Kyoto protocols, signed what I quite frankly think were stupid targets and then had no plan after 10 years in office to even implement those," said Harper.

Earlier in the day, interim Liberal leader Bob Rae called Canada an international "pariah" - a term more typically associated with North Korea or Iran.

Meanwhile, Greenpeace anti-oil sands campaigner Mike Hudema is standing by his comments that the Conservatives "imposed a death sentence on many of the world's most vulnerable populations by pulling out of Kyoto."

Hudema doesn't think that goes too far, even though the Kyoto accord covers less than a third of the world's emitters of greenhouse gases.

He also talked about the "human dimension" of delayed action on what he called the climate crisis.

Still, Hudema is unwilling to say that China or the United States "imposed a death sentence" on vulnerable populations by not being subject to Kyoto commitments.

"Being in Canada and being a Canadian, we focus on the Canadian government," Hudema said.

As the rhetoric heats up, an environmental bureaucrat says it isn't obvious to him that just because Environment Minister Peter Kent has announced a Kyoto pullout, his office is free of its legal mandate to update Parliament on progress in meeting Kyoto targets.

"I think now there's a lot of work available for lawyers to determine the impact of Mr. Kent's announcement," said federal Environment Commissioner Scott Vaughan.

He expects to have a plan in place for what comes next in "the next week or so."