SINGAPORE (Reuters) - Singapore will close all mosques for at least five days for deep cleaning to prevent the spread of coronavirus after two congregants were thought to have been infected during an Islamic conference in neighboring Malaysia.

The Islamic Religious Council of Singapore said the closures would take effect Friday, and that authorities are trying to track down around 90 Singaporeans who attended the three-day religious event in Malaysia’s capital Kuala Lumpur.

Singapore’s health ministry said two of nine new cases announced on Thursday were of people who had attended the event, which has also been linked to at least 12 infections in Malaysia.

A number of other religious groups have canceled physical gatherings in Singapore in recent weeks to try and halt the spread of a virus that has infected 187 people in the city-state.