SYDNEY: The nearly three-year search for Malaysia Airlines Flight 370 ended Tuesday, possibly forever — not because investigators have run out of leads, but because the countries involved in the expensive and vast deep-sea hunt have shown no appetite for opening another phase.

Late last year, as ships with high-tech search equipment covered the last strips of the 120,000-square kilometer (46,000-square mile) search zone, experts concluded they should have been searching a smaller area immediately to the north. But by then, $160 million had already been spent by Malaysia, Australia and China, who had agreed over the summer not to search elsewhere without pinpoint evidence.

The transport ministers of those countries reiterated that decision Tuesday in the joint communique issued by the Joint Agency Coordination Center in Australia that announced the search for Flight 370 — and the 239 people aboard the aircraft — had been suspended.

"Despite every effort using the best science available, cutting-edge technology, as well as modeling and advice from highly skilled professionals who are the best in their field, unfortunately, the search has not been able to locate the aircraft," said the agency, which helped lead the hunt for the Boeing 777 in remote waters west of Australia.

"Accordingly, the underwater search for MH370 has been suspended. The decision to suspend the underwater search has not been taken lightly nor without sadness."

Relatives of those lost on the plane, which vanished during a flight from Kuala Lumpur to Beijing on March 8, 2014, responded largely with outrage. A support group, Voice 370, issued a statement saying that extending the search is "an inescapable duty owed to the flying public."

Without understanding what happened to the plane, there's a "good chance that this could happen in the future," said K.S. Narendran, a member of the group.

But last year, Australia, Malaysia and China — which have each helped fund the search — agreed that the hunt would be suspended once the search zone was exhausted unless new evidence emerges that pinpoints the plane's specific location. More than after of those aboard the plane were Chinese.

Since no technology currently exists that can tell investigators exactly where the plane is, that means the most expensive, complex search in aviation history is over, barring a change of heart from the three countries.

There is the possibility that a private donor could offer to bankroll a new search, or that Malaysia will kick in fresh funds. But no one has stepped up yet, raising the bleak possibility that the world's greatest aviation mystery may never be solved.

For the families of the aircraft's 227 passengers and 12 crew members, that's a particularly bitter prospect given the recent acknowledgment by officials that they had been looking for the plane in the wrong place all along.

In December, the transport bureau announced that a review of the data used to estimate where the plane crashed, coupled with new information on ocean currents, strongly suggested that the plane hit the water in an area directly north of the search zone.