OTTAWA — Quebec is warning Stephen Harper it may go to court, if necessary, to block any attempt by the federal government to unilaterally reform the Senate.

Intergovernmental Affairs Minister Pierre Moreau reiterated his province's view Monday that the federal government alone cannot reform the appointed upper chamber.

Moreau said any change must be done through a constitutional amendment, approved by at least seven provinces.

"It would be, I think, illegal to proceed unilaterally with a federal law and that's what we're opposed to," Moreau told The Canadian Press.

"We are not objecting to modernization of the Senate itself, but we think that any change for that chamber should go through a constitutional amendment ... That is the official position of Quebec; it has been the same for the last 20 years and more."

In the past, Ontario, Newfoundland and New Brunswick have also objected to the federal government proceeding unilaterally with Senate reform.

Harper is expected to introduce next month -- for the fourth time -- two Senate reform bills. One would impose term limits on senators and the other would encourage provinces to elect nominees who would then be appointed to the Senate by the prime minister.

Previous attempts to pass the bills were thwarted by opposition parties in the House of Commons or the Liberal majority in the Senate. But having finally secured a majority in both houses of Parliament, Harper's Conservative government is hoping this time the bills can be speedily passed and put into effect by as early as the fall.

Backed by some constitutional experts, the Harper government believes the bills do not amount to significant changes to the make-up of the Senate and, as such, can be done unilaterally by the federal government.

But Quebec, among other provinces, begs to disagree.

"They have their constitutional professionals, we have our constitutional experts as well," said Moreau.

"But it's not our constitutional experts nor their constitutional experts who will decide what should be done at the end of the story."

He suggested the courts will have to settle the matter.

"At the end, it could be a referral to the Supreme Court or to the court of appeal as far as provinces are concerned."

Several provinces, including Quebec, have urged the federal government to refer the issue to the Supreme Court, to determine whether it would be constitutional for the federal government to proceed with the proposed Senate reforms on its own. The Harper government has consistently refused.

Alternatively, a province could refer the matter to its own high court, which in Quebec would be the court of appeal.

Until now, the Harper government has proposed imposing a term limit of eight years on senators, who can currently sit for up to 45 years until age 75. In the coming version of the bill, the government may propose a longer term of 10 or 12 years -- a move aimed at ensuring a prime minister with two majority mandates would not end up appointing every member of the 105-seat chamber.

However, Moreau said the length of the term makes no difference. As far as Quebec is concerned, no term limit can be imposed without a provincially-approved constitutional amendment.

Moreau said having gained control over both parliamentary chambers is not sufficient reason for Harper to push ahead unilaterally with Senate reform.

"You know, we have a majority government as well here in Quebec and it's not because you have a majority that you can do anything. You know, there's public opinion ... and you have to take into consideration how will react your neighbour and how will react your partners in the federation."

Moreau said creation of an appointed Senate was part of the bargain struck at Confederation in 1867. The chamber was supposed to represent the regions and act as a counterbalance to representation by population in the elected House of Commons.

Electing senators could "change the balance" between the partners of Confederation, he said, "so that's the reason why we think any change at this level should require a constitutional amendment."