Australia is upgrading its outbound  "do not travel"  warning to a ban that prevents most Australians from heading overseas. The federal government will use biosecurity powers to prevent a small number of people who continue to ignore the travel warning from heading overseas from Wednesday. Exceptions will include aid workers, those who need to travel on compassionate grounds or for people whose travel is essential for work. READ: COVID-19 wipes out 35 percent of global airline capacity, with more to come. Prime Minister Scott Morrison told a press conference on Tuesday night that the number of people leaving Australia was now "very, very low" but there were still a number of people defying the do not travel advice and looking to head overseas for leisure travel. Morrison said the government had been making the point for some time that no-one should be getting on a plane and going overseas for some time. "They can't do it because when they come home, that's when they put Australians at risk,'' he said. " I had hoped that would have been fully complied with and I've got to say, Australians have been pretty good about it. But we need to put that arrangement in place." Asked when the ban would come into effect, Morrison said a directive was being worked on overnight and would come into force Wednesday. Australia already has in place bans on incoming foreigners but Australians are flocking back to the country while commercial travel is still available and many of the nation's more than 2100 confirmed cases have been acquired overseas. Officials say the majority of the overseas cases had a recent history of travel to Europe or the Americas and cruise ships have proved a problem. The travel ban was part of a number of new measures introduced as Australian tightens coronavirus restrictions and expands limits on gatherings to include weddings, funerals and other events. Pubs, restaurants, cinemas and other venues are already off-limits and Australians are being urged to stay home and respect social distancing requirements as authorities try to curb the spread of the disease. Australia is among a number of countries tightening travel restrictions and Hong Kong on Wednesday will join other global airline hubs such as Singapore and Dubai in banning transit passengers. Cathay Pacific, which had already announced it was slashing capacity to just 4 percent, has a comprehensive list of entry restrictions on its website although these are subject to change. One country that is was still allowing air services on Tuesday was Qatar. Qatar Airways said it was still operating flights to more than 70 cities worldwide. It said it was constantly reviewing its flights to see where there was more demand or requests for services and where possible would add flights or put on bigger aircraft. "We appreciate this is a difficult time and that many people around the world are trying to find a way to get home,'' it said "At Qatar Airways we continue to operate more than 150 flights per day so that as many people as possible can get home safely to their loved ones."