Ten new Omicron cases were detected in Delhi on Friday, taking the nationwide tally of the heavily mutated variant of COVID-19 to 90 in the country.

The daily count of fresh coronavirus cases in Delhi has also gone up to 85 in the last 24 hours giving rise to concern.

Delhi has reported 20 cases of the new variant since the first case was registered  on December 5. Ten of these patients have been discharged, Health Minister Satyendar Jain said on Friday.

Many international passengers have been testing positive for Covid lately, he added.

Maharashtra, the state with the highest overall Covid cases, has so far recorded the most number of Omicron cases at 32. Karnataka, Gujarat, Kerala, Tamil Nadu, West Bengal, and Andhra Pradesh are the other states that have detected cases of the new variant. Most of the Omicron has been found in people returning from overseas travel.

The Centre has asked states to step up surveillance and send samples for genome sequencing to keep infections in check.  Restrictions for travellers arriving from abroad have already been put in place.

The WHO had warned on Tuesday that the Omicron strain was spreading at an unprecedented rate and had affected at least 77countries.

Meanwhile, United States President Joe Biden on Thursday warned of a "winter of severe illness and death" for those unvaccinated against COVID-19 as cases of the new variant surge.

The United Kingdom has registered the highest number of Omicron cases worldwide with 11,708. Denmark is next on the list with 9,009 such cases. Norway has the third-highest number of cases (1,792) followed by South Africa (1,134).

Studies are still on to see whether Omicron has the capacity of breaking through vaccines protection which is an area of serious concern.