Hong Kong Cable Television on Tuesday quoted sources from China's health ministry as saying a formal announcement would be made later.
The 20-year-old woman is in hospital in the southern city of Guangzhou.
China, meanwhile, denied reports that a sick man in the southern town of Shenzhen was a possible SARS case.
Shenzhen garment trader Chen Xiaohe, 38, had SARS-like symptoms a month ago, but doctors determined he was suffering from a form of bacterial pneumonia, Xinhua news agency said.
The Xinhua comment came as Asia faced a new health scare in bird flu, with the World Health Organisation (WHO) confirming that the disease had killed three people in Vietnam.
Chen was put in intensive care on 10 January for "respiratory distress, coupled with other symptoms such as pneumonia, respiratory failure and failure of other organs in the chest", the agency said.
WHO launches probe
"Shenzhen city has strictly followed the requirements for reporting set by the World Health Organisation," Zhou Jun'an, head of the health bureau of Shenzhen city, was quoted as saying.
The SARS scare has put a damper
on the Chinese holiday season
"There has been no confirmed or suspected SARS case in Shenzhen since winter."
WHO researchers in Guangdong, working with the health ministry, are examining all possible sources of SARS infection - animals, humans and the environment.
The government has ordered a cull of civets cats - weasel-like animals that are a local delicacy and the prime suspect - in hopes of averting an outbreak.
The virus first emerged in Guangdong late in 2002 and went on to infect more than 8000 people in nearly 30 countries, killing nearly 800.
While Guangdong officials have urged the public not to panic, indications that the latest scare could also have a knock-on effect emerged on Tuesday with Beijing travel agencies cancelling all tours to the popular province.
Tours to Guangzhou, Shenzhen, Zhuhai and other areas have been brought to a halt due to the three cases, the Beijing Times said.
China came under fire for its poor handling of SARS last year, but authorities, along with the global health body have been racing to unravel the mystery of this year's cases.
With China's major holiday, the Spring Festival approaching, Guangdong officials have carried out a week-long slaughter of civet cats in an attempt to stem the spread of the disease.