Singapore has joined more than 40 other countries in tightening restrictions on travellers arriving from the United Kingdom, following the emergence of a new coronavirus strain there that appears to be more contagious.

From 11.59pm tonight, all long-term pass holders and short-term visitors with travel history to Britain within the last 14 days will not be allowed to enter or transit through Singapore, said the Ministry of Health (MOH) yesterday.

This ban will also apply to all those who had obtained prior approval for entry into Singapore.

As for returning Singaporeans and permanent residents, they will have to be tested on arrival, and again towards the end of their 14-day stay-home notice period at dedicated facilities.

Education Minister Lawrence Wong, who co-chairs the multi-ministry task force combating Covid-19, told reporters yesterday that Singapore has been monitoring the situation in Britain very closely.

"The preliminary assessment is that (the new strain) is 70 per cent more infectious, which is significant, and therefore we think it is prudent to stop all incoming travellers from the UK during this period until we are able to learn more about this new strain of the virus," he said.

While precautions are in place, Singapore has decided to cut exposure to such arrivals.

"We still need to understand, beyond the fact that it is more transmissible, whether it is going to lead to a more severe disease, or will there be other impact," he said. "Having this additional precaution now is necessary and prudent, because of the uncertainty and the risk."

BioNTech chief executive Ugur Sahin said his company was confident that its vaccine - co-developed with Pfizer - works against the UK variant, but further studies are needed to be completely sure: "The likelihood that our vaccine works... is relatively high."

But if needed, "we could be able to provide a new vaccine technically within six weeks", he added.

In the meantime, many countries in Europe have stopped flights from Britain. Hong Kong and India have also done so.

The World Health Organisation said the new strain was a normal part of a pandemic's evolution.

Mr Wong said the strain has yet to be detected in the Republic, but added that Singapore has to stay vigilant and monitor how the strain is spreading, and constantly adjust measures at its borders and within the community.

MOH noted that the British authorities are investigating whether the strain is associated with any change in disease severity, antibody response or vaccine efficacy. It added that it will evaluate the data as it emerges and review border measures accordingly.

In addition, short-term travellers holding an air travel pass with travel history to Australia's New South Wales state within the last 14 days will not be allowed to enter Singapore from tonight.

Singapore residents and long-term pass holders with such travel history will be subject to a seven-day stay-home notice.

The move follows a new cluster of cases in Sydney that led the state to impose a five-day lockdown in the Northern Beaches area, which is slated to end today and will be reviewed by the state.

Travellers from other parts of Australia will continue to be subject to a Covid-19 test on arrival in lieu of a stay-home notice.