All of the patients have been isolated and their close contacts are under medical observation, the Wuhan Municipal Health Commission said.
China has reported several cases of acute pneumonia in Hubei Province's Wuhan City, 1,500 km northeast of the border, since December, according to the ministry's General Department of Preventative Medicine.
Health workers evacuate "infected patients" from a building during a SARS outbreak drill in Hong Kong in November 2004.
The notice added that hospitals were planning to release two of the 27 infected people in the next few days after some more treatment, while 18 other patients are in a stable condition.
Tony Ko Pat-sing, chief executive of the Hospital Authority, said three people were admitted to Princess Margaret Hospital, Tuen Mun Hospital and Alice Ho Miu Ling Nethersole Hospital as suspected cases, but their fevers had already gone, and two were sent home. Thus far, there have been no clear indications of human-to-human transmission of the disease, the commission said.
The highly contagious virus, a form of pneumonia, killed hundreds of people in China and Hong Kong in the early 2000s.
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An investigation and cleanup were under way at a seafood market in the city where most of the patients worked.
The Chinese Ministry of Health is investigating the source of the infection and seeks to contain the outbreak.
China dismissed its health minister at the time, Zhang Wenkang, after being criticized by the WHO for covering up and underreporting the number of SARS cases.
According to local media cited by the SCMP report, the Huanan Seafood Market sold other animals, such as birds, pheasants, and snakes, along with organs of rabbits and other wildlife, triggering worries about the potential jump of an unknown virus to humans at the market. The city has not received any Wuhan-related severe pneumonia cases, Secretary for Food and Health Sophia Chan told reporters on Thursday.
Wuhan police said eight people had been punished for "publishing or forwarding false information on the internet without verification".
From Friday, extra infra-red thermographic cameras will be used to check whether a traveler coming in on a flight or by fast train from Wuhan has a fever, the Hong Kong government said on Thursday evening.
Taiwan has implemented similar measures, its Centre for Disease Control said Tuesday.
None of the regional authorities have expanded inspections and screening measures to cover other parts of China.