Singapore reported 120 new coronavirus cases on Sunday, by far its highest daily rise, and quarantined nearly 20,000 migrant workers in their dormitories.
Of Sunday's new cases, 116 were locally transmitted and many were linked to two dormitories that house migrant workers, who will now have to stay in their rooms for 14 days.
The number of new cases is a 60 percent increase over the 75 reported on Saturday, which was the previous biggest daily rise. Singapore has reported a total of 1,309 infections and six deaths from the novel coronavirus.
Tens of thousands of blue-collar foreign workers live within close quarters in various dormitories in the tiny Southeast Asian nation, an island city-state. They form a significant part of the labor force, working in sectors from construction to cleaning.
The spike in cases comes two days before the country will begin closing schools and most workplaces for a month as part of tighter restrictions to combat the Covid-19 disease.
Singapore was one of the worst-hit countries when the virus first spread from China in January, but a strict surveillance and quarantine regime helped stem the tide. Recent spikes in locally transmitted cases have, however, raised fresh concerns.
The government is also converting a large exhibition venue to east of the island into a medical facility to accommodate patients who have mostly recovered from Covid-19 but may still be infectious. It will be the second such facility after a hotel was converted last month to isolate up to 500 such people.