World Health Organisation said on Tuesday that Omicron strain of coronavirus is 'spreading at an unprecedented rate' and its presence is possible 'probably in all countries, news agency AFP reported.

"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. Omicron is spreading at a rate we have not seen with any previous variant," Dr Tedros A Ghebreyesus, Director-General of WHO said on Tuesday.

Meanwhile, Omicron cases topped the figure of 50 all over India on Tuesday, as 8 new cases were discovered in Maharashtra and 4 in Delhi. Of 8 Omicron cases in Maharashtra, 7 were reported from Mumbai alone. The state health department said that none of the Omicron cases reported on Tuesday from Mumbai had a history of international travel.

(With inputs from agencies)