The World Health Organization warned Tuesday that the new coronavirus variant Omicron was spreading at an unprecedented rate and was likely already present in most countries around the world.

"77 countries have now reported cases of Omicron, and the reality is that Omicron is probably in most countries, even if it hasn't been detected yet," WHO chief Tedros Adhanom Ghebreyesus told reporters, adding that "Omicron is spreading at a rate we have not seen with any previous variant."

(With input from agencies)