BEIJING - There are no "probable" or confirmed human cases of swine flu in China, but authorities are investigating several people with suspicious symptoms, the World Health Organization said Tuesday.

China earlier pledged open and quick reporting of any cases of swine flu in the country as it ordered an all-out effort to prevent an outbreak.

The government, which was heavily criticised for initially covering up the SARS epidemic in 2003, has made fighting the disease its "central task", said a statement issued after a Cabinet meeting chaired by Premier Wen Jiabao.

The State Council said in a statement it had ordered a raft of measures including the establishment of a "direct reporting system on the epidemic leading to early discovery, early reports, early diagnosis, early quarantine and early treatment".

"As soon as cases are discovered in our borders they must be publicly announced in a timely manner."

The State Council ordered the creation of a joint monitoring body uniting staff from the health and agriculture ministries, the state quarantine and inspection bureau and other relevant departments.

"We have to maintain high vigilance, adopt effective measures and rigorously guard against the epidemic to protect the health and safety of the masses," the government statement said.

"The meeting ordered all regions and all departments to make prevention of human cases of swine flu their central task."

China initially tried to deny the existence of the 2003 outbreak of Severe Acute Respiratory Syndrome, or SARS, and only owned up after it spilled over into other countries.

The meeting chaired by Wen marked a sharp escalation in China's response, as the situation overseas has quickly worsened. The health ministry had at the weekend merely said it was "paying close attention" to the situation.

The State Council ordered strict monitoring of people arriving in China from affected areas and strengthened supervision of the pig-raising industry, pig markets, and the import and exports of pigs.

Beijing had already banned hog and pork product imports from Mexico and parts of the United States.

"Because the epidemic situation in some countries is still developing, cases are mounting, and the affected area is expanding, the possibility of transmission to our country has not been eliminated," it said.

China's National Tourism Administration meanwhile ordered travel agencies to halt tours to Mexico in light of the swine flu outbreak.

It also advised Chinese tourists to avoid travelling to Mexico in the near future.

The National Tourism Agency is run by China's Cabinet, the State Council, according to its website.

The number of "probable" deaths from swine flu rose in Mexico from 149 to 152, Mexico's health minister said, of about 2,000 possible cases.

The virus has sickened victims from the US to New Zealand, with New York City Mayor Michael Bloomberg saying more than 100 students at a parochial school in Queens contracted an illness that was probably swine flu.

The number of confirmed swine flu cases in the US more than doubled Monday to 44.

- AFP/ir