That is 10 more nations that just a week ago, the body said.
The South African variant, which like the UK mutation is more infectious, has been found in 23 countries, the WHO added.
A weekly update on the pandemic provided by the WHO said there was too little information about a third, Brazilian variant “to assess if there are changes in transmissibility or severity”.
So far, vaccines seem to remain effective against the new variants, but there are signs that some of the new mutations may undermine tests for the virus and reduce the effectiveness of antibody drugs as treatments.
“We're in a race against time” because the virus “may stumble upon a mutation” that makes it more dangerous, Dr Pardis Sabeti, an evolutionary biologist at the Broad Institute of MIT and Harvard, told the Associated Press.
On Wednesday, a study revealed the vaccine developed by Pfizer and BioNTech does protect against the UK coronavirus variant.
In the report, which has not yet been peer-reviewed, researchers from BioNTech collected blood samples from 16 people who had received the Pfizer vaccine in previous clinical trials.
They found that a lab-made version of the virus – with all the mutations resembling the so-called B117 variant – was neutralised by antibodies.
The WHO weekly update said there were 4.7 million new cases globally in the past week, a decline of 6 per cent from last week.
The number of new deaths has climbed to a record high at 93,000, a 9 per cent increase from last week.
“Over 2 million people have now lost their lives to Covid-19,” the WHO briefing said. “The Americas, Europe, and southeast Asia regions showed declines in new cases, with Europe showing a 15-per-cent decline and the Americas and southeast Asia regions showing more moderate declines of 2 per cent and 1 per cent respectively.
“On the other hand, the eastern Mediterranean, African, and western Pacific regions reported increases in new cases, with the western Pacific showing the largest increase (14 per cent).
“All regions reported increases in new deaths; case incidence continues to be one of the primary drivers of mortality – where increases in the number of Covid-19 related hospitalizations and deaths follow large numbers of cases after a short time lag.”