TORONTO (AP) —Canada's Conservative environment minister said Monday that signing the Kyoto Protocol on climate change was one of the previous government's biggest "blunders" but he declined to confirm a report that Canada will formally pull out of the treaty.

As United Nations climate negotiations opened in South Africa on Monday, CTV News in Canada reported that Ottawa will announce its formal withdrawal from the Kyoto accord next month. The report said Prime Minister Stephen Harper and his Cabinet have already decided to formally withdraw from the protocol, but that it won't be announced until Dec. 23. after the conference ends.

Environment Minister Peter Kent said he would neither confirm or deny the report.

"This isn't the day. This is not the time to make an announcement," he said.

Canada, joined by Japan and Russia, said last year it will not accept new commitments, but renouncing the accord would be another setback to the treaty concluded with much fanfare in 1997. No nation has formally renounced the protocol.

"Kyoto is the past," said Kent, who reiterated there is no point to signing a new accord as long as countries like the U.S., China and India—the world's three largest emitters—face no legal constraint.

"If there is urgency to address climate change, this is not the time for the world's major emitters to sit on the sidelines," he said.

The protocol, initially adopted in Kyoto, Japan, in 1997, is aimed at fighting global warming. Canada's previous Liberal government signed the accord but the Harper government never embraced it.