The Canadian government dismissed the Kyoto protocol as a thing of the past on Monday as new global climate-change talks began in Durban, South Africa.
However, it declined to confirm a report that it is to pull out of the treaty soon.
In an unsourced report, CTV News said the government would announce its formal withdrawal from Kyoto on 23 December, when the Durban talks are over.
Environment Minister Peter Kent said in Ottawa that the decision by a previous government to sign the protocol as "one of the biggest blunders they made."
Canada says it backs a new deal to cut global emissions of greenhouse gases but insists it has to cover all nations, including China and India, which are not bound by Kyoto's current targets, Reuters reports.
No nation has yet formally renounced the treaty.