A controversial bill calling for the federal government to honour its international commitments under the Kyoto Protocol is about to enter its final reading.

The bill was put forward by the Liberals last year and has the support of all opposition parties, who together have successfully moved the bill forward through its first two reading.

Both the Bloc Québécois and the NDP have pledged to support the Liberal bill, which is designed to force the minority government to meet Canada's Kyoto Protocol obligations.

Despite the Conservatives decrying the bill as a toothless tiger, the bill holds strong implications for government

If it passes its final reading, as its expected to do, the Conservatives would face a publicly embarrassing defeat and may be forced to accept the greenhouse gas limits set forward in the international agreement - something they have been consistently opposed to since coming to power.

The third reading and final reading of the bill takes place tonight.