Health authorities in the Netherlands said on Sunday they had discovered at least 13 cases of the new Omicron variant among passengers on two flights from South Africa.

A total of 61 passengers from the flights tested positive for COVID-19 and almost all are in quarantine at a hotel near Amsterdam's Schiphol airport, while a few have been allowed to go into home quarantine. 

"The Omicron variant has so far been identified in 13 of the positive tests. The investigation has not yet been completed. The new variant may be found in more test samples," the National Institute for Public Health said in a statement.

The two flights by Dutch national carrier KLM from Johannesburg arrived in Amsterdam respectively at 10:30 a.m. and 11:00 a.m. local time. 

Around 600 passengers were tested after the flights' arrivals and those who tested negative were asked to go into home quarantine if remaining in the country. 

(With input from agencies)