They were worried about contracting Covid-19 while overseas, but Mr Eden Ong's family still opted to travel to Thailand to visit relatives on March 13.

Two days later, they found out that all residents returning from Asean countries must serve a 14-day stay-home notice.

"We chose to carry on with our trip as there was nothing we could do about the travel restrictions," Mr Ong told The New Paper.

The polytechnic student, 19, disagreed with the view that those who travelled abroad were irresponsible.

"We still cared about safety and made it a priority to practise good hygiene habits and social distancing," he said.

With Singaporeans now advised to defer all travel abroad, National Development Minister Lawrence Wong warned yesterday that those who still choose to travel will have to face consequences.

The Government is mulling additional measures to address this and will announce specifics once they are ready.

All returning residents serving the stay-home notice must use their personal leave, and their employers cannot claim the $100 daily allowance from the Ministry of Manpower.

But even after stern warnings to take the travel advisories seriously, Singaporeans and permanent residents are still heading overseas, Mr Wong, who is co-chair of the multi-ministry task force on Covid-19, said at a press briefing yesterday.

"We don't know the reasons why... It may well be that they have very exceptional reasons to travel. But we do not want to see a third wave of imported cases from returning Singaporeans," he said.

"We are already having to digest this wave of returning Singaporeans now. I think if we have to experience third (or) fourth recurring waves of imported cases, it will be very, very challenging."

Calling the coronavirus outbreak an unprecedented crisis, Mr Wong also announced new measures to significantly tighten Singapore's border.

All short-term visitors will no longer be allowed to enter or transit through Singapore from 11.59pm today.

Work pass holders and their dependants will be allowed to return only if they work in essential service sectors such as healthcare and transport.

Of the 23 new cases yesterday, 18 were imported, with all but one returning residents and long-term pass holders.

Dr Jeremy Lim, partner for health and life sciences at consultancy firm Oliver Wyman, told TNP that the imperative is to reduce the number of cases.

UNNECESSARY RISK

He said: "The majority of new cases last week are imported and closing this door to infections as best we can is essential...

"Singaporeans travelling abroad may bring the virus back when they return, straining resources and adding unnecessary risk of local spread."

Asked about measures to dissuade Singaporeans from travelling, Dr Lim, who teaches at the NUS Saw Swee Hock School of Public Health, said it would depend on how many are doing it.

"If the number is small, a more targeted approach makes sense.

"If large, then a blanket ban would be expedient, with an appeal process for genuine cases such as visiting very ill relatives overseas."

Singaporeans such as Ms Joyce Tan, 47, are already shelving travel plans.

The managing director of a manufacturing firm lost $3,000 after cancelling two trips this month, one to Bangkok with her two daughters and another to Finland with a group of childhood friends.

She is also planning to cancel a third trip to Taiwan in May.

"We can't afford to catch the virus and transmit to any family members at home... That is the main consideration," she said.

"If everyone has the same thought, that we suffer a little now by sacrificing our travelling, we'll be able to get through this outbreak quickly."

Echoing these sentiments yesterday, Mr Wong said the objective of keeping Singaporeans safe cannot be achieved with government measures alone.

"We do need everyone to take responsibility...

"If we all cooperate, step up during this period, we will be able to ensure that we are successful in suppressing and slowing down the spread of the virus."

ADDITIONAL REPORTING: NUR HIDAYA JAMAL