A second major Chinese hospital was sealed off and the government was forced to deny martial law was imminent as roadblocks were thrown up around Beijing to combat SARS. The Ditan Hospital, treating more than 100 SARS patients including foreigners, was quarantined with some 600 medical staff told they cannot go home, hospital officials said.

"Before we were isolating the infectious disease ward within the hospital compound. Now the whole hospital is cordoned off," said a hospital official surnamed Zhao.

It follows the quarantining of the People's Hospital Thursday where more than 1,000 workers and patients were spending their second day in isolation after up to 55 Severe Acute Respiratory Syndrome cases were found.

The Beijing Youth Daily said the 1,000 included doctors, nurses, other staff members, patients and anyone else who happened to be in the hospital when it was ordered shut.

Nineteen confirmed or suspected cases of Severe Acute Respiratory Syndrome had been found in the hospital, the paper said but medical sources told AFP the number of cases was as many as 55.

The Ditan was one of several hospitals designated to take SARS patients and specializes in infectious diseases.

Most of the doctors in the hospital are living in a hotel nearby, but it was not immediately clear whether they were forced to stay there or if they were living there by choice to avoid infecting their families.

Earlier this month, the hospital said it had treated several foreigners, including a Finnish man who died, a Canadian and two Taiwanese.

Its isolation came as new quarantine measures took effect for all those who had come in contact with the deadly SARS virus as the government struggles to combat a virus that has killed 39 in the capital and infected more than 1,600.

Nationwide the death toll stands at 110, with 2,422 confirmed cases.

The quarantine applies to hospitals, factories, construction sites, hotels, restaurants, office buildings, residential buildings, villages, schools and other designated places where the virus has been found.

Roadblocks have also been thrown up around the city of 13 million, reinforcing residents fears that the Chinese capital is to be isolated.

Police officers manning the roadblocks said their purpose was to stop people from heading into neighbouring Hebei province where just six SARS cases have been reported so far.

"If they don't have medical proof from the proper disease control centre that they don't have SARS symptoms, then we won't let them through," one mask-clad policeman on the border told AFP.

An official circular from the Beijing municipal government meanwhile said all college students and teachers were "prohibited from leaving" the capital for the May Day holidays, which have been cut back from seven days to five.

It said any students who insist on leaving must have written documents proving they are healthy, the Xinhua news agency reported.

Students who have poor health and are from rural areas, western parts of the country or areas with SARS are prohibited from leaving altogether.

As panic over the galloping epidemic intensified, the Beijing government was forced to issue a denial that martial law was imminent to control the spread of SARS.

"The government will not close expressways and the airport for this purpose," Cai Fuchao said at a press conference, Xinhua reported.

PHOTO CAPTION

Chinese security guards patrol the perimeter of the capital's biggest hospital, the Beijing People's Hospital, where 1,000 people have been quarantined after up to 55 people were found to have contracted SARS.