Britain is one of several countries to have announced cases of the new variant on their soil, including Germany, Italy and the Netherlands, even though most European countries have shut down flights from southern African nations, where the variant was first identified.
The head of the World Health Organisation in Africa on Sunday urged countries to follow the science rather than imposing flight bans in a bid to contain the new variant.
"With the omicron variant now detected in several regions of the world, putting in place travel bans that target Africa attacks global solidarity," said WHO regional director general Matshidiso Moeti.
South Africa's president Cyril Ramaphosa on Sunday became the latest leader from the region to denounce the flight ban and the economic damage it is doing to the countries affected.
The WHO on Friday declared the recently discovered strain a variant of concern, but scientists are still trying to assess how dangerous it is.