Singaporeans must be mentally prepared for a spike in coronavirus cases here, Minister for National Development Lawrence Wong said yesterday.

Mr Wong, who co-chairs the multi-ministry task force combating the spread of Covid-19 here, made these remarks after announcing a series of enhanced measures to keep the virus at bay.

These include barring entry to visitors with a history of recent travel to Iran, northern Italy and South Korea, as well as a swab test for visitors who are symptomatic at checkpoints.

The Health Ministry has also asked Singaporeans to defer non-essential travel to Iran, northern Italy, South Korea and Japan. These countries have seen spikes in cases.

In addition, the Ministry of Manpower said that from 11.59pm today, all work pass holders and their dependants with recent travel history to Iran, northern Italy and South Korea will have to obtain its approval before commencing their journey to Singapore, regardless of their nationality.

Upon arrival, they will be placed on a 14-day Stay-Home Notice.

Mr Wong said: "Despite our very best efforts, we have to be mentally prepared for the number of infected cases in Singapore to go up."

He noted that those here may have become accustomed to the number of cases in Singapore increasing by "just a handful" every day.

"But this may not be the norm, and it can change very easily. You see this in other countries too, where you have very few cases for a few days and then suddenly, one incident occurs... and there is a sharp spike in cases and sustained transmission. This has happened elsewhere; it can happen in Singapore too," he said.

He added that countries which do not report a lot of cases may still have undetected cases going around.

"We cannot stop it from happening. The only way to stop it is if you were to isolate and shut ourselves out from the world. But I don't think that is a tenable situation," he said.

Despite this, said Mr Wong, measures such as border controls still have their purpose at this stage.

"We can still identify where the sources of risk are, and we can take appropriate measures to reduce the risk from these infected sources.

"By doing so, we flatten the epidemic curve in Singapore. We buy ourselves time, and we avoid a situation where our hospitals get overwhelmed by a sudden surge of cases," said Mr Wong.

Singapore's tourism sector is expected to feel the crunch from the new travel restrictions, a spokesman for the National Association of Travel Agents Singapore (Natas) told The Straits Times yesterday.

However, he added: "The association will monitor the situation closely with our travel agents, gather feedback and work with the relevant agencies to explore what kind of support can be provided."

Mr Samson Tan, chief executive of travel agency GTMC Travel, said the new restrictions will not heavily impact the travel sector, but only because it has already been very much affected by the Covid-19 outbreak.

Mr Tan, who is also a Natas executive committee member, said: "In the last few weeks, fewer Singaporeans are already travelling to South Korea. With this new advisory against travelling there, I think tour groups will probably stop going completely."

He added that although travel to Japan has eased by about 80 per cent in recent weeks, some Singaporeans are still willing to go to its southern parts, where fewer cases have been reported.

"Japan and South Korea are usually in the top five favourite destinations for Singaporeans, but now, travel sentiment is very bad overall."

Editorial note: This article has been edited for clarity.