The Canadian government remains concerned that an amended "Buy American" clause is still included in the final version of the proposed U.S. economic stimulus package, despite "some improvements" in the provision, Prime Minister Stephen Harper said Friday.

The provision would require public works projects receiving money from the federal stimulus package to use U.S.-made iron, steel and manufactured goods. It could be signed into law by President Barack Obama as early as Monday.

After fierce pressure from Canada, the European Union and several prominent U.S. corporations, lawmakers in Washington added a caveat to the provision to clarify "Buy American" must not violate international trade agreements.

The change is directed at calming countries that are members of NAFTA and the World Trade Organization, but the U.S. Congress stopped short of removing the clause entirely from the bill.

Speaking to reporters in Montreal on Friday following an aerospace funding announcement, Harper again noted the new U.S. president has also warned against the perils of starting a trade war.

"There were some improvements as it went through the congressional process," said the prime minister, who is scheduled to meet with Obama in Ottawa next week.

"But obviously, all of us remain concerned, and I think President Obama himself has said that he wants to ensure that these stimulus packages do not lead to protectionist measures in the U.S. or anywhere else."

The stimulus bill, currently containing $789 billion US in spending, was passed in the House of Representatives on Friday and moved back to the Senate.

A vote on the bill in the Senate was scheduled for 5:30 p.m. ET Friday evening in an attempt by Democratic lawmakers to meet a deadline of passing the plan before a recess begins next week.

With files from the Associated Press