SINGAPORE - Two people who travelled to Wuhan have been diagnosed with pneumonia, said the Ministry of Health (MOH) on Friday evening (Jan 17).

They are a 64-year-old male Chinese national and a 61-year-old female Singapore resident.

"Both cases have been admitted for further assessment and treatment, and isolated as a precautionary measure," a ministry spokesman said. "They are in stable condition."

The two people did not visit the seafood wholesale market in Huanan, from where the new bug is thought to have emerged.

Investigations are ongoing to establish whether their illnesses are linked to the Wuhan disease cluster, MOH said.

These two cases bring the total number of people in Singapore who have been suspected of having the Wuhan virus to five.

The first two were a three-year-old girl and a 26-year-old man, both of whom were Chinese nationals. They had visited Wuhan - the capital of central China's Hubei province - but subsequently were tested negative for the virus.

The third case, reported on Thursday, is a 69-year-old Singaporean man who travelled to Wuhan but did not visit the seafood wholesale market in Huanan. The man has been tested negative for the virus.

On Thursday, a Japanese man became the second confirmed Wuhan virus case to be reported outside China.

The first death from the mystery virus occurred in China on Jan 9. The 61-year-old man, who had serious underlying medical conditions, was confirmed to have been infected with the new viral pneumonia.

The World Health Organisation has said that a newly emerging strain of coronavirus, the same virus that causes severe acute respiratory syndrome, or Sars, could have caused the current outbreak.

It is preparing for the possibility of a wider outbreak, given the upcoming Chinese New Year holidays when millions of Chinese will be travelling home or abroad.

Countries in the region are on high alert, with Indonesia and Thailand intensifying airport screenings.