A top Canadian health official has warned people that they might have to be "chained to a bed" if they violate the strict Sars quarantine rules in Toronto.
Canada has altered the way it defines suspect cases
The Toronto authorities are investigating four deaths linked to Sars which have raised fears that the outbreak could be spreading further than previously thought.
The deaths last week happened at a hospital away from areas identified as being affected by the pneumonia-like illness.
"I don't know how people will like this, but we can chain them to a bed if that's what it takes," said Ontario Health Minister Tony Clement.
He was referring to reports that some people in quarantine were not sticking to the required 10-day isolation period.
China sees improvement
Meanwhile, China on Sunday reported no new Sars fatalities and only two new cases - the lowest figures for a single day since authorities began issuing daily bulletins in April.
Known death tolls:
Mainland China: 348
Hong Kong: 298
Source: WHO/local authorities
The death toll from Severe Acute Respiratory Syndrome in mainland China remained at 332, with more than 5,000 reported cases.
The authorities in Hong Kong said three more people died of Sars on Sunday, bringing the overall death toll to 281.
In Taiwan - where four new cases were reported - the authorities have launched a nationwide "take-your-temperature" campaign, handing out free thermometers.
Toronto health officials said that autopsy tests had shown that some of the four dead patients were carrying the corona virus thought to be the cause of Sars.
The hospital - on the outskirts of the city - has closed its emergency units and walk-in clinics as a precaution.
So far, 30 people in the city are known to have died from Sars.
The BBC's Lee Carter in Toronto says there have been persistent reports of people refusing to remain in quarantine.
Our correspondent says the most blatant example is the case of students from a suburban high school shut down because of one case of probable Sars, who were seen out shopping or even visiting other schools.
On Saturday, Mr Clement said Ontario could employ extra powers if people refuse to remain in quarantine.
"We have the tools in place now, it's a question of whether they're necessary or not and if we think they're necessary we're going to use them," he said.
Our correspondent says that those who attended two funeral services a week ago in Toronto are the latest people to be asked to go into quarantine.