The world's largest AIDS conference kicks off in Toronto on Sunday with a star-studded news conference and a four-hour benefit concert.

Dignitaries such as former U.S. president Bill Clinton, software billionaire Bill Gates and his wife Melinda, and actor Richard Gere will be among the speakers at the six-day International AIDS Conference, which is expected to draw 20,000 delegates.

Artists to perform at the concert include Alicia Keys, Chantal Kreviazuk, Barenaked Ladies, Our Lady Peace, Amanda Marshall and the Blue Man Group. The show runs from 7 to 11 p.m. at the Rogers Centre.

While the conference gives Canada a world stage to demonstrate leadership in the global fight against the deadly disease, Prime Minister Stephen Harper has declined to attend, citing other commitments.

"I still hope that he'll be here, and our doors will always be open to Mr. Harper," conference co-chairman Dr. Mark Wainberg told CTV Newsnet on Saturday. "We would never refuse a Canadian prime minister."

Health Minister Tony Clement and International Co-operation Minister Josee Verner will attend in Harper's place.

Wainberg, who is also director of McGill University's AIDS centre in Montreal, said Canada needs to act now in its fight against the epidemic.

"Well, our theme is 'Time to Deliver' and it really means that we've been promising so many people so many things now for such a long time, it's vital that we finally deliver on some of these promises," he said.

"And that means, among other things, getting the drugs that we have successfully developed so far to people in developing countries who will almost certainly die unless we have some means of insuring that they have access. And we're talking about people by the tens of millions.

"AIDS kills something like 6,000 to 7,000 thousand people a day -- that really puts it way ahead of anything else we can imagine."

Wainberg said the disease easily kills more people than any military conflict or natural disaster. He said too many people don't take AIDS seriously, and the general public needs to get involved and engaged, as do government leaders.

"AIDS touches a lot more families in Canada than you would imagine, but there's still unfortunately a stigma attached to an HIV diagnosis and too many people just don't want it to be known that they or someone in their families may be touched by this epidemic," said Wainberg, adding too many people not directly affected don't get involved.

He said "terribly alarming" statistics show the numbers of AIDS cases in Canada continually climbs each year, and it's "absolutely shameful" that almost one-third of all new cases occur in aboriginal communities.

"We have to do a much better job, that's for sure," Wainberg said.

Key research and papers on clinical trials and new drugs will be discussed thoroughly at the conference, he said.