Health Minister Dzulkefly Ahmad said the three individuals infected were Chinese nationals and related to the 66-year-old man that was confirmed by Singapore health authorities to have tested positive for the virus.
The newly-identified coronavirus can cause pneumonia, which has been deadly in some cases. It is still too early to know just how dangerous it is and how easily it spreads between people.
The infected individuals were a 65-year-old woman, who is the wife of the man detected with the virus in Singapore, and their two grandsons, aged 11 and 2, Dzulkefly said.
The three have been admitted to Sungai Buloh hospital in Kuala Lumpur for treatment and were considered in stable conditions, the minister said at a news conference.
In a separate statement, Malaysia Airports said it has heightened screening of all passengers and crew arriving from China at gateway airports across the country to minimize the potential spread of the virus.