JOHANNESBURG, Dec 1 (Reuters) - A senior Botswana health official said on Tuesday that 16 of the total 19 cases of the Omicron coronavirus variant detected in the country were asymptomatic, while President Mokgweetsi Masisi said travel bans on its citizens were unfair and unjustified. Pamela Smith-Lawrence, Acting Director of Health in the Ministry of Health and Wellness, told Reuters in an interview that the majority of the 19 people who were found to be infected with the new Omicron variant have already tested negative. While 16 people were asymptomatic, the remaining three had "very, very mild" symptoms. Botswana on Friday said the country was investigating certain mutations of the coronavirus that were found in four foreign nationals who were in the country on a diplomatic mission. It has since reported another 15 cases of the new variant. While it is still not established where Omicron first emerged, on Nov. 25 South Africa, followed by Botswana a day later, announced they had detected a new variant whose mutations were different from the dominant Delta variant. Buildings are seen in the Central Business District (CBD) in the capital Gaborone, Botswana, September 21, 2018. REUTERS/Siphiwe Sibeko Buildings are seen in the Central Business District (CBD) in the capital Gaborone, Botswana, September 21, 2018. REUTERS/Siphiwe Sibeko This prompted immediate air travel curbs on southern African countries from several European and Asian countries, a decision which has been criticised by both South Africa and Botswana. "The decision to ban our citizens from travelling to certain countries was hastily made and is not only unfair but is also unjustified," President Masisi said on state-run TV. "In light of the new variant, we are constantly monitoring our COVID-19 detection indicators and they remain stable," Masisi said, adding that the country has experienced a decrease in infections and deaths over the last three months. The four foreign nationals, aged between 30 and 65, came to Botswana on Nov. 7, tested positive on Nov. 11 and the new mutations were found on Nov. 22, Smith-Lawrence said, adding the government uploaded the data on the international database the next day. Without giving further details, she said that 14 out of the 19 people so far detected with the variant were foreign nationals. She said within the next two to three weeks the government would be in a position to give more clarity on whether Omicron is more virulent than its predecessors or not.