Prime Minister Stephen Harper has come under fire for his noted absence from the 16th International AIDS Conference, which opens in Toronto on Sunday.

About 24,000 delegates from 132 countries are expected to discuss a range of subjects — including funding, drugs, research and cultural issues — at the gathering, which runs through next Friday.

"We're having in excess of 20,000 people coming to Toronto. We're hosting the largest HIV event ever in the world, and somehow our political leadership is going to look the other way. It's just not acceptable," Dr. Julio Montaner, a world-renowned AIDS researcher from the University of British Columbia, told the Canadian Press.

Conference co-chair Dr. Mark Wainberg  agreed, saying he was disappointed by the prime minister's decision to turn down an invitation to open the conference.

"I think he's made a mistake, quite honestly," Wainberg told CP.

Harper travelled to Iqaluit on Saturday, where he promised to build a deep-water port and a military training centre in Nunavut as part of his government's commitment to secure Canada's claim to the Northwest Passage. He will visit Yellowknife and Whitehorse later in the week.

Speakers at the Toronto conference include:

• Stephen Lewis, UN special envoy on HIV/AIDS in Africa.
• Bill Clinton, the former U.S. president.
• Bill and Melinda Gates, who have recently pledged to spend $30 billion to fight diseases including AIDS.

Nearly 65 million people worldwide have been infected HIV since it was identified 25 years ago. AIDS has killed more than 25 million people in the same time frame.

Officials have estimated that 11,000 new cases of HIV and 8,000 deaths occur every day, the bulk in sub-Saharan Africa.

The conference, which runs every two years, began in 1985 in Atlanta, when a group of researchers and doctors gathered to share information about the growing pandemic.

With files from the Canadian Press