TORONTO (REUTERS) - Canadian legislators on Monday voted to back the government's plans to bomb Islamic State in Iraq and Syria (ISIS) positions in Syria, a move that opposition parties say threatens to drag Canada into a long war.

The House of Commons approved the plan 142-129. The result was never in doubt, since the ruling Conservatives have a majority in the chamber.

The vote also approved the extension of Canada's six-month mission by a year to the end of March 2016.

Canada has around 70 special forces troops in northern Iraq and six Canadian jets are taking part in US-led bombing attacks against ISIS in Iraq.

Prime Minister Stephen Harper, who has made security a main plank of his platform in the run-up to an October election, last week said Canada needed to strike against Islamic State safe havens in Syria.

Polls show Harper will have a tough time retaining power in October. The New Democrats and the Liberals - the two main opposition parties - say Canadian attacks in Syria will only help prop up President Bashar al-Assad.