Hong Kong has ceased to function as an international aviation hub as it curbs inbound flights and quarantines arriving passengers, according to a trade group representing hundreds of airlines worldwide.

“It’s effectively off the map now, and I think it’s going to be difficult for Hong Kong to recover,” Willie Walsh, director general of the International Air Transport Association, said at a briefing Wednesday. “It’s going to lag significantly behind the recovery that we’re seeing elsewhere and has led to a tough time for all airlines operating there.”

Even the city’s shortened isolation requirements for arriving passengers—quarantine was halved to one week this month—will deter travelers, Walsh said.

The IATA chief said that with much of the rest of Asia reopening he remained optimistic Hong Kong could start to relax its border restrictions.

However, Hong Kong is still banning flights even after rolling back some of the world’s strictest inbound travel curbs. There’s been increasing frustration over the city’s closure for much of the past two years due to pandemic restrictions.

“The restrictions there have been very severe and have led directly to the cancellation of a lot of services with airlines—effectively finding it incredibly difficult, if not impossible to operate there,” added Walsh.

IATA has warned places that continue to attempt to lock out the disease, rather than managing it, risk missing out on enormous economic and societal benefits through the restoration of international travel. The group represents almost 300 airlines accounting for 83% of global air traffic.

Singapore Airlines Ltd., Emirates, Cathay Pacific Airways Ltd., Qatar Airways QCSC, Korean Air Lines Co. and Malaysia Airlines were slapped with week-long bans this month after breaching Hong Kong’s so-called circuit-breaker mechanism. A stoppage can be meted out if three or more Covid-19 cases are found on the same flight, or if there’s one confirmed infection and another non-compliant passenger.

Hong Kong eased a raft of travel measures on April 1, including lifting an outright ban on inbound flights from nine countries, including the U.S., the U.K. and Australia, and reduced quarantine for inbound travelers to one week.

Walsh said the feedback IATA was getting from airlines was that quarantine remained discouraging, and people would not fly in the current environment unless they really had to.