From next Tuesday night, all travellers from higher-risk areas will have to take a polymerase chain reaction test (PCR) for Covid-19 within 72 hours before departing for Singapore.
These travellers will still have to serve a 14-day stay-home notice (SHN) after arriving and be tested at the end of their quarantine.
Currently, only those who have recently travelled to India, Indonesia and the Philippines have to test negative for Covid-19 to enter or transit through Singapore.
The new requirement, which aims to reduce the risk of imported cases, is part of Singapore's double-barrelled strategy to contain the virus as the country moves towards phase three of its reopening.
It will take effect at 11.59pm on Nov 17, and does not apply to Singaporeans or permanent residents.
As Singapore intensifies its testing regime, Covid-19 tests will also be made more accessible.
Currently, those who are well and do not need to meet specific requirements - such as pre-departure or pre-event tests - cannot request a Covid-19 test.
From Dec 1, any company or person who needs to be tested can pay for a PCR test at about 600 clinics and private healthcare providers.
Imported cases and community cases are two broad areas of risk that the Government is monitoring closely, said Education Minister Lawrence Wong who co-chairs the Multi-ministry Taskforce handling the crisis. "On both fronts, we are taking careful and controlled measures to reopen and to resume activities," he added.
Reopening Singapore's borders is an existential issue because of the country's small size and need to connect with the world, he said.
"It's not just for economic activities, but also for our social and community needs, because we must allow families to reunite and we would also want to facilitate the entry of foreign domestic workers who are taking care of our loved ones," Mr Wong said.
Travellers from lower-risk countries or regions have to either take a PCR test - the gold standard for Covid-19 tests - upon arrival, or serve a seven-day SHN at home and be tested at the end of that period. These countries include Brunei, New Zealand, Vietnam, Australia and mainland China.
Those from the higher-risk group have to serve their 14-day SHN at dedicated facilities. In some instances, they will be allowed to serve this notice at home, but will have to meet requirements like wearing electronic monitoring devices.
Mr Wong cautioned that while community cases are currently very low, "it is inevitable" that the risk of clusters forming will rise when Singapore enters phase three and more activities resume.
Singaporeans must be "mentally prepared" for the number of community cases to go up to double digits - and perhaps even to the 20s and 30s, he added.
The country's testing capability has been stepped up to prevent large, out-of-control clusters from forming, he said. For the same reason, Singapore also needs to strengthen its contact tracing capabilities through the expansion of SafeEntry and TraceTogether.
"If we all do cooperate and do our part, we can move confidently towards phase three," he added.
"And, even in phase three, ensure that the reopening of our borders and the resumption of activities do not result in large clusters forming again, because all of us do not want to have to go through another circuit breaker."