OTTAWA -- A source close to former prime minister Jean Chretien says the former prime minister is in a Hong Kong hospital today because of a kidney stone.

The source, who was not authorized to speak on Chretien's behalf, tells The Canadian Press that Chretien passed a kidney stone, "which is painful but not serious," and that everything was going to be fine.

Chretien, 85, was scheduled to speak at the U.S-China Trade and Economic Relations Forum in Hong Kong today.

Instead he was taken to hospital shortly after landing in the semi-independent Chinese territory Monday evening.

Tung Chee-hwa, a former leader of the semi-independent Chinese territory, told attendees at conference that Chretien would not be able to make it to the event.

Expanding trade with China was a theme in Chretien's time in office and he's continued working on business links between China and North America since he went back to private life.

"I want to deliver an apology because Jean Chretien, the prime minister of Canada, he arrived here very late last night," Tung said, according to a transcript of his remarks. "And we were supposed to have breakfast together. But he has not been well. And as a precaution, we have taken him to a hospital. We think it is going to be all right. So wish him all the best."