PERTH, Australia (AP) — The weekslong search for Malaysia Airlines Flight 370 is "an extraordinarily difficult exercise" but it will go on as long as possible, Australia's prime minister said Monday.
Tony Abbott told reporters in Perth, the base for the search, that although no debris has been found in the southern Indian Ocean that can be linked to the plane, searchers are "well, well short" of any point where they would scale the hunt back.
The Boeing 777 disappeared March 8 while flying from Kuala Lumpur to Beijing with 239 people aboard, and after experts sifted through radar and satellite data, they gradually moved the hunt from seas off of Vietnam, to areas west of Malaysia and Indonesia, and then to several areas west of Australia.
"This is an extraordinarily difficult exercise .... we are searching a vast area of ocean and we are working on quite limited information," Abbott said, adding that the best brains in the world and all the technological mastery is being applied to the task.
"If this mystery is solvable, we will solve it," he said.
He said the search that has been going on for more than three weeks is operating on guestimates "until we locate some actual wreckage from the aircraft and then do the regression analysis that might tell us where the aircraft went into the ocean."
Ten planes were either over the search zone or heading there by late Monday afternoon, and another 10 ships were scouring the area, about 1,850 kilometers (1,150 miles) west of Australia. More than 100 personnel in the air and 1,000 sailors at sea were involved in Monday's hunt, with some sections of the zone expected to experience low clouds and rain. It takes planes about 2 1/2 hours to get to the area, allowing a five-hour search before they must return to Perth.
The aircraft and ships are crisscrossing a search zone that was redefined based on radar and satellite data from the Boeing 777, although after several days no debris has been found that can be linked to the flight, officials say. Only fishing equipment and other flotsam have been spotted.
Former Australian defense chief Angus Houston on Monday began his job of heading the new Joint Agency Coordination Center, which will oversee communication with international agencies involved in the search. The Perth-based center will position Australia to shoulder more of Malaysia's coordination responsibilities as the search drags on indefinitely.
Houston will also play a prime coordination role when victims' families travel to Australia in the weeks ahead.
Abbott said he was not putting a time limit on the search. "We owe it to everyone to do whatever we reasonably can and we can keep searching for quite some time to come ... and, as I said, the intensity of our search and the magnitude of operations is increasing, not decreasing."
The Ocean Shield, an Australian warship which is carrying a U.S. device that detects "pings" from the flight recorders, was expected to leave Perth on Monday for the search zone, a trip that will take three to four days. The Australian Maritime Safety Authority, which is coordinating the search, said it would first conduct sea trials on Monday afternoon to test the search equipment on board.
The search area remains vast, so investigators are hoping to first find debris floating on the ocean surface that will help them calculate where the plane crashed into the water.
Meanwhile, several dozen Chinese relatives of Flight 370 passengers visited a Buddhist temple near Kuala Lumpur on Monday to pray for their loved ones. They offered incense, bowed their heads in a moment of silence, knelt several times during the prayers and lowered their heads in kowtows. Buddhist nuns handed out prayer beads to them. "You are not alone," one nun said. "You have the whole world's love, including Malaysia's."
Several of the relatives were overcome with emotion, tears streaming down their faces.
The family members later made a brief statement to journalists, expressing their appreciation to the Chinese government and the people of Malaysia and the volunteers who have been assisting them. They bowed as a show of gratitude, but also said they were still demanding answers.
"To those who are guilty of harming our loved ones, hiding the truth, and delaying the search and rescue, we will also definitely not forgive them," said a family representative, Jiang Hui.
The relatives' comments Monday were seen as a small conciliatory move after they staged an angry protest in front of reporters on Sunday at a hotel near Kuala Lumpur. At the time, they chanted slogans, raised banners and called on the Malaysian government to apologize for what they dubbed missteps in the handling of the disaster.
Wong reported from Kuala Lumpur. Associated Press writers Scott McDonald and Eileen Ng in Kuala Lumpur; Malaysia; Kristen Gelineau in Sydney; and Rod McGuirk in Canberra, Australia, contributed to this report.