Ministers have faced fierce pressure over the issue, and last month an Africa action group founded by U2 frontman Bono, warned an earlier version of the bill was too soft on brand-name drugs firms.

Canada claims to be more advanced that any other country in pushing through a World Trade Organization (WTO) pact to allow generic drug manufacturers to supply cheap versions of medicines patented by major pharmaceutical companies.

But despite changes to the bill, some leading international aid groups criticised it as being too friendly to commercial pharmaceutical giants.

The Canadian HIV/AIDS Legal Network said one proposed change in the law would actually invite commercial pharmaceutical companies to engage in "lengthy and vexacious litigation" if they believed so-called generic drug firms were making a profit from supplying patented drugs to developed countries.

A commercial drug company, according to Legal Network director Richard Elliott, "can initiate this process merely by alleging" a generic firm was making an undue profit.

David Morley, executive director of Medecins Sans Frontieres, said "the bill has come a long way" and, in general he welcomed changes in the planned legislation.

But he was concerned about a new clause which would include a specific list of medicines for which the government could override a patent held by a commercial phamaceutical company.

Morley told reporters even the WTO had not demanded that and, because medicine was changing so rapidly, there should be more flexibility for the government to authorize new drugs for the aid programme.

Bono's group DATA warned last month in a letter to Prime Minister Paul Martin on the issue "that the world needs Canada to shoulder its commitments."

"Canada made the solemn millennium promises along with other richer nations to help the poorest help themselves develop." he wrote.

"The richest nations must keep these promises to the poor."

TERRA.WIRE