A special parliamentary committee studying proposed clean air legislation was expected to finish its work on the hotly debated bill Thursday after considering it clause by clause one more time.

Bill C-30, Canada's clean air act, introduced by the governing Conservatives in October, is due to be submitted to the House of Commons Friday. It was sent to the committee after it passed first reading.

Opposition members, who form a majority on the committee, have completely revamped the bill so that it barely resembles its original form.

It now contains short-term, mid-term and long- term targets for reducing greenhouse gas emissions. It includes a commitment to a system of international emissions carbon trading.

And it provides for what is being called a green investment bank where companies that fail to meet targets pay penalties instead.

Prime Minister Stephen Harper is said to be opposed to international emissions carbon trading and has said he thinks short-term greenhouse gas targets are not realistic.

The opposition introduced more than 50 amendments to the bill, while the Conservatives did not introduce a single amendment.

"It's now in the hands of the prime minister to decide whether he is going to abide by the will of the committee and, ultimately, the will of Parliament," Liberal MP David McGuinty told CBC News Wednesday.

"What we have done is put Humpty Dumpty back together again in a way that perhaps the prime minister might not like it."

Changes could spark election

The government could either accept the changes in the bill as proposed by the committee or use them to trigger an election call, according to the Canadian Press.

McGuinty said the bill now includes much of the clean air plan proposed by Liberal Leader Stéphane Dion. The committee was scheduled to consider the bill clause by clause for two hours Thursday morning.

"The opposition parties have actually come up with a new strong agreement on a series of issues. The government MPs on the committee don't know how to respond," McGuinty said.

"The Conservatives have not tabled a single amendment to improve the bill that they, by their own admission, sent to a committee to get fixed," he said.

The bill was originally drafted to give the federal government power to reduce air pollution and greenhouse gases. When it was introduced, the government said it was the centrepiece of its green plan.

Harper said at the time: "We have a plan that is going to replace rhetoric with results, a plan that is going to move from short-term headlines to long-term progress, a plan that is going to get things done on the environment."

Under the first reading version of the bill, there was no mention of the Kyoto Protocol and there were no hard caps on greenhouse gas emissions until 2020 or 2025, but the government said it would seek to cut greenhouse gas emissions by 45 to 65 per cent by 2050.

Also, its emissions regulations on large polluters did not take effect until 2010.

Under Kyoto, the previous Liberal government pledged that Canada would reduce greenhouse gas emissions by six per cent below 1990 levels by the five-year commitment period of 2008 to 2012.

with files from the Canadian Press