The World Health Organization (WHO) Director-General Tedros Adhanom on Sunday slammed countries that have imposed travel restrictions on travelers from southern Africa due to the emergence of the Omicron variant of COVID-19.

South African scientists were the first to identify the variant, which has since been detected in many other countries around the world.

Latest reports indicate that Omicron was already present in Europe before the travel bans were announced.

"It remains disappointing that some countries continue to block direct flights from southern Africa due to the Omicron variant. It's also dismaying that some countries aren't accepting negative COVID-19 tests from countries of origin & instead require tests only from 3rd countries," Tedros wrote on Twitter.

"Respect is owed to the science and technology expertise in African countries as well as their transparency and sharing, including data related to the Omicron variant of concern. This is helping to ensure a safer world for all people everywhere," he added.

African leaders have condemned the travel bans. Instead calling upon the wealthy nations to appreciate the continent's efforts that enabled the strain to be detected in good time.

The countries restricting travel include the United States, which barred entry to travelers from South Africa, Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique and Malawi.

"We are all concerned about the new Covid variant and owe South Africa's scientists our thanks for identifying it before anyone else did," Malawi's President Lazarus Chakwera said.