TORONTO, Dec 2 (Reuters) - Canada"s plan to require novel coronavirus tests for all but U.S. arrivals on international flights risks causing "chaos" and long lines if all passengers are expected to get tested at airports, industry groups said. The move, announced Tuesday, comes as the travel season kicks into gear and could stretch airport resources as well as testing holiday-makers" patience, they said. Daniel Gooch, president of the Canadian Airports Council, said airports cannot test all overseas arrivals on-site without long wait times. "Do we really want people waiting for hours for a test in a customs hall?" he asked by phone on Wednesday. "We want to avoid chaos. And we want to ensure that travellers who have booked trips are comfortable to travel." Canada on Tuesday said it will require people arriving internationally by air, except from the United States, to take a COVID-19 test, seeking to halt the spread of the Omicron coronavirus variant. read more Currently, only randomly selected passengers from international flights are tested at airports by private companies the government contracts. The announcement came as the country"s aviation sector, battered by the pandemic, had been looking forward to a stronger holiday season this year. Canadian public health authorities did not say Wednesday when the policy will come into effect, who will administer the tests or whether the tests will be administered on-site or through take-home kits. Airports are pushing for the latter. Tori Gass, a spokesperson for Toronto"s Pearson International Airport - Canada"s largest - said in an email that "a combination of onsite and off-airport testing must be considered to accommodate the volume of tests contemplated." Some travellers, meanwhile, who had rushed to book trips amid loosening restrictions just weeks before, were having second thoughts. "I know various clients who have decided to cancel and are now looking at what refunds they"ll be able to get," said Marty Firestone with Travel Secure insurance, adding that the travel landscape had been getting better. "Now we"ve taken two steps back," he said.