Hong Kong has issued a red alert against non-essential travel to South Korea, where the death toll from Middle East Respiratory Syndrome (MERS) has risen to seven.

Eight new infections brought the total number of cases to 95 in the largest outbreak outside Saudi Arabia, following the diagnosis of the first patient on May 20.

The number of new South Korean cases was a sharp drop from 23 on Monday, but the number of schools closed grew to 2,208, including 20 universities.

The latest fatality on Tuesday was a 68-year-old woman who had an existing heart ailment and was infected by a MERS patient at a hospital in Seoul.

"At this stage, to issue a clear message is something the Hong Kong government thinks is necessary," Hong Kong's number two official Carrie Lam told reporters.

A red alert is defined as a "significant threat", according to the Hong Kong government, and means people should "adjust travel plans" and "avoid non-essential travel".

The Travel Industry Council of Hong Kong cancelled all tours to South Korea that were scheduled to set off between now and June 30, excluding cruises, with 10,000 to 12,000 travellers to be affected, the city's public broadcaster reported.

MERS facts Middle East Respiratory Syndrome Coronavirus is known as MERS and MERS-CoV

Middle East Respiratory Syndrome Coronavirus is known as MERS and MERS-CoV All recorded cases can be traced back to the Middle East

All recorded cases can be traced back to the Middle East Dromedary camels are thought to be the source of infection

Dromedary camels are thought to be the source of infection The virus can be spread person-to-person

The virus can be spread person-to-person Symptoms include fever, cough, shortness of breath and breathing difficulties

Symptoms include fever, cough, shortness of breath and breathing difficulties Severe cases can have a rapid onset of respiratory illness, like pneumonia

Severe cases can have a rapid onset of respiratory illness, like pneumonia There is no vaccine to prevent the virus Source: health.gov.au

On Monday, Hong Kong upgraded its response to the outbreak in South Korea to "serious".

Nam Kyung-pil, governor of Gyeonggi province, which surrounds the South Korean capital, Seoul, said 32 of its large general hospitals have joined the campaign to fight the outbreak by offering to take in anyone who is showing MERS symptoms.

"We are fighting two wars; the war against the disease and the war against fear," Mr Nam said.

The South Korea government said it hoped to halt the outbreak of the virus by the end of the week.

South Korean president Park Geun-hye has called for an all-out national effort to eradicate the outbreak, which has been spreading since a 68-year-old businessman brought it home from a Middle East trip last month.

All subsequent infections in South Korea have occurred in healthcare facilities and been traced to the original patient.

The World Health Organisation (WHO) began work on a joint mission with South Korean doctors and officials to review the country's response and analyse the virus.

The WHO has not recommended any curb on travel, but thousands of tourists have cancelled plans to visit South Korea.

WHO specialist Peter Ben Embarek said South Korea's response had been aggressive and was getting better, adding it should still not be surprising if there were a few cases of infection coming outside of hospitals.

Macau, Singapore take precaution against MERS

The Chinese territory of Macau required masks for people entering local healthcare facilities as a precaution against MERS, and advised residents to avoid travel to South Korea unless absolutely necessary.

All subsequent infections in South Korea have occurred in health care facilities and been traced to the original patient.

Singapore said it would start screening body temperatures of passengers arriving from South Korea from late Tuesday (local time).

Taiwanese health authorities issued a travel alert to cover all of South Korea late on Tuesday, widening its caution on travel to the country.

Earlier, Taiwan had issued its travel alert only for Seoul, while putting the rest of the country on a less serious "watch" level.

Some 2,892 people who may have had contact with MERS patients have been put under quarantine, some in hospitals but most at home.

Authorities have said they are using mobile phones to track people who violate quarantine.

South Korea's new cases bring the total of MERS cases globally to 1,244, based on World Health Organization (WHO) data, with at least 446 related deaths.

Reuters/AFP