However, the agency was continuing to advise that people avoid visiting the capital, Beijing.
The United Nations health agency also expressed new concern Friday about Toronto after a visitor from North Carolina caught SARS during a visit to Canada’s business capital.
While the WHO criticized Toronto for allowing the disease to resurface, the group’s top infectious disease expert praised steps China took to contain the disease.
After confirming that there had been no new SARS cases for more than 20 days — twice the disease’s maximum incubation period — the WHO dropped its travel alert for the Chinese provinces of Hebei and Shanxi, Inner Mongolia and the city of Tianjin.
“SARS is no longer a potential threat to international travelers to these regions,” the WHO said in a statement.
It also removed these and a number of other Chinese areas from the list of places where SARS was still feared to be spreading, a move tantamount to declaring them SARS-free.
Despite the fact that Beijing, once the SARS capital of the world, had seen a dramatic decline in new cases, WHO said it still needed to know more about the pattern of the disease there.
“In Beijing, we don’t believe the situation is fully under control, and nor do the Chinese authorities,” WHO spokesman Iain Simpson told a news conference.
Taiwan, which is pushing to have its travel alert lifted, had a similar problem, Simpson said.
“We still have concern about some of the recent cases in Taiwan, some that can’t be linked to known chains of transmission,” he reported.
Separately, authorities in Taiwan on Friday began investigating whether the island had underreported SARS deaths.
After jumping from south China to Hong Kong and Vietnam in March, the disease, which is fatal in 15 percent of cases, quickly spread by air travel to about 30 countries.
New cases worldwide have dropped below 10 per day, and WHO said Thursday the global outbreak seemed to be ending. But Dr. David Heymann, the WHO’s director of communicable diseases, cautioned Friday that it was too soon for health authorities to let up their guard.
“China has made huge strides in its effort to contain the outbreak of SARS,” Dr. Heymann said. “The key thing now is to maintain vigilance and build up China’s disease surveillance system. Public health authorities in China and around the world must continue to watch out for new cases of SARS to ensure that it does not emerge again elsewhere.”
Public health officials hope that vigilance may help prevent other regions from experiencing the resurgence of the virus that occurred in Toronto. The disease has in recent months appeared to be under control there, but it erupted again in May.
The U.N. health agency Friday shifted Toronto from Pattern B to Pattern C SARS transmission, its most severe classification. The WHO’s Simpson said the shift came because it was unknown how a man from North Carolina contracted the respiratory ailment during a visit to Toronto last month.
Toronto appeared to have brought the outbreak under control until May 22, when a second cluster of cases was reported.
“Toronto let down its guard in mid- to late-May,” Simpson said Friday. “Somewhere along the line, the surveillance system wasn’t effective enough or someone wasn’t vigilant enough and cases got through the net.”
But Simpson added there were no immediate plans to issue a travel warning for Toronto as the WHO did in April, a move that severely disrupted the local economy.