Singapore has temporarily suspended crew changes and crew vaccinations for seafarers with recent travel history to several African countries over fears about exposure to a potentially more contagious variant of the Covid-19 virus.

The countries affected are Botswana, Eswatini, Lesotho, Mozambique, Namibia, South Africa and Zimbabwe, the Maritime Port Authority (MPA) said in a port circular.

This includes sign-on crew travelling to Singapore by flight as well as sign-off crew from vessels that have called at the seven countries within the last 14 days, as well as those crew have transited those same countries on their connecting flights to Singapore.

Late last month Singapore’s Ministry of Health (MoH) imposed new restrictions on travellers from those same African countries.

Returning Singapore citizens and permanent residents will have to serve a 10-day stay-home notice at dedicated facilities, the MoH added.

The new variant, called B.1.1.529, or Omicron, was first detected in South Africa and is speculated to have caused a sharp rise in Covid-19 cases there.

The MoH has said these border restrictions will remain in place for at least four weeks and will be reviewed after this period.

Singapore's transport minister recently told local media that the city-state has air links with only one of the seven countries.

There is one flight from South Africa to Changi Airport every day, with most passengers on board said to be in transit.

The MoH said that as of 1 December 2021, the total number of individuals who have completed their full regimen/received two doses of Covid-19 vaccines constitutes 96% of the eligible population and 87% of the total population.

"As a percentage of total population, 87% has received at least one dose, and 27% has received their booster shots,” it added.

On Thursday, Singapore reported its first two imported Covid-19 cases who tested preliminarily positive for Omicron.

The World Health Organization (WHO) designated the Omicron variant on 26 November following its discovery in South Africa.

Since then many countries have enacted travel bans from various parts of the world, with the WHO reporting as many as 24 countries may have cases.