In a weekly online press briefing, the World Health Organization’s Africa branch said the continent had recorded 107,000 extra cases in the week to Sunday, compared with 55,000 in the previous week.

Omicron “is reaching more countries in Africa”, it said, adding that research was being stepped up to see whether the new variant was specifically behind the sharp rise.

The biggest surge in numbers – 140% on average – was in the south of the continent.

However, in South Africa, which discovered the new variant last month, “severe cases remain low,” the WHO said in a statement.

“Emerging data from South Africa indicates that Omicron may cause less severe illness,” it said.

“Data which looked at hospitalisations across South Africa between Nov 14 and Dec 4 found that ICU (intensive care unit) occupancy was only 6.3%.

“(This) is very low compared with the same period when the country was facing the peak linked to the Delta variant in July.”

The agency reiterated its objections to travel restrictions, which it said had been issued by more than 70 countries and were overwhelmingly aimed at southern Africa, even though countries in the region had been “transparent with their data”.

It also called on countries to step up vaccinations – only 7.8% of the continent’s roughly 1.2 billion people have been jabbed.

The biggest laggards in immunisation are Chad, Djibouti and Democratic Republic of Congo.

A new vaccine supply system is being set in place to help African countries distribute them more easily, said Richard Mihigo, WHO Africa’s vaccination programme coordinator.