China's Health Ministry announced a new confirmed case of SARS (search) on Saturday, but said the patient — the country's fourth case this season — had already been discharged from a hospital.

The official Xinhua News Agency identified the man as a 40-year-old doctor from the southern city of Guangzhou, and gave his family name, Liu.

"The patient has been released from hospital recently," Xinhua said, without specifying when.

Liu became ill on Jan. 7, suffering from a high fever and a sore throat, Xinhua said. He checked himself into a hospital in Guangzhou, the capital of Guangdong (searchprovince, on Jan. 13, it said.

On Jan. 18, "his body temperature dropped to normal and his condition stabilized," Xinhua said.

Liu denied having any contact with animals or SARS patients, the report said.

Health officials have been monitoring 48 people who had contact with him, but none have showed any symptoms, it said.

Telephones were not answered at the Ministry of Health on Saturday. An official at the Guangdong anti-SARS office in Guangzhou (search), said he "wasn't clear" about any details on the case. He refused to give his name.

The first known case of severe acute respiratory syndrome emerged in Guangdong in November 2002. A subsequent worldwide outbreak killed 774 people last year, including 349 in mainland China, and sickened more than 8,000 before subsiding last July.

This season's three other patients in China — a businessman, a waitress and a television producer — have been released from the hospital in recent weeks. All also were from Guangzhou.

The World Health Organization said it was important for health authorities to trace how the patients got sick as soon as possible.

"Now we have four cases without a concrete source of infection," said Roy Wadia, a spokesman for the World Health Organization's office in Beijing. "It's something we're very concerned about."

China is also waging a battle against bird flu, which has ravaged much of Asia. The disease has killed millions of chickens and at least 10 people in as many countries.

China's first confirmed case was announced Tuesday in a duck in the southern region of Guangxi. On Friday, the government announced confirmed cases in its central provinces of Hunan and Hubei and suspected cases in the financial capital of Shanghai and the provinces of Anhui in the east and Guangdong.