Australian Prime Minister Tony Abbott said there was no time limit on the hunt for Malaysia Airlines Flight MH370, missing for more than three weeks in the Indian Ocean with 239 people on board.
A New Zealand Air Force Orion and another nine planes from Australia, Japan, China, Korea, the United States and Malaysia as well as ships will resume scouring a massive area in the Indian Ocean some 2000km west of Perth on Monday, search authorities said.
"I'm certainly not putting a time limit on it," Mr Abbott told reporters after meeting flight crews at Pearce airbase in Perth. "The intensity of our search and the magnitude of operations is increasing, not decreasing," he said, adding that searchers owed it to grieving families of passengers to continue the hunt.
Malaysia says the plane, which disappeared less than an hour into a flight from Kuala Lumpur to Beijing on 8 March was likely diverted deliberately far off course. Investigators have determined no apparent motive or other red flags among the 227 passengers, including two New Zealanders, or the 12 crew.
Families have strongly criticised Malaysia's handling of the search and investigation, including the decision last week to say that, based on satellite evidence, the plane had crashed in the southern Indian Ocean, Reuters reports.
Mr Abbott rejected suggestions his Malaysian counterpart had been too hasty to break that news, given that no confirmed wreckage from the plane has been found and its last sighting on radar was northwest of Malaysia heading towards India. "No, the accumulation of evidence is that the aircraft has been lost and it has been lost somewhere in the south of the Indian Ocean," he said.
China has also been critical in Malaysia's handling of the case, but in a sign of softening, the official China Daily said it was understandable that not all sensitive information could be made public.
More flotsam found
Dozens of items have been spotted since Australian authorities moved the search 1100km north after new analysis of radar and satellite data, but none has been linked to Flight MH370.
The new search area, while closer to Perth and subject to calmer weather, is also closer to an area of the Indian Ocean where currents drag all manner of flotsam and rubbish. The greatest problem remains the vast search area, roughly the size of Poland or New Mexico.
Among the vessels due to join the search in the coming days is an Australian defence force ship, the Ocean Shield, that has been fitted with a sophisticated US black box locator and an underwater drone.
However, they cannot be used until "conclusive visual evidence" of debris is found, US Navy spokesman Commander William Marks told CBS's Face the Nation programme.
If no location is found, searchers would have to use sonar to slowly and methodically map the bottom of the ocean, he said. "That is an incredibly long process to go through. It is possible, but it could take quite a while."
An Australian Navy ship has been equipped with two different devices to help locate the flight data recorders from the missing Malaysia Airlines plane.
The United States has provided the specialist equipment and operators for the Ocean Shield, which was due to sail from Perth on Monday.
Captain Mark Matthews from the US Navy says the first device is a towed pinger locator, which listens for acoustic emissions from the flight data recorders, and the second is an remote-operated underwater vehicle. He says finding surface debris remains a critical first step in narrowing where the wreckage might be.
Families want answers
Thirty relatives of Chinese passengers travelled to Kuala Lumpur on Sunday to press the authorities for answers. Chanting: "Tell us the truth", the relatives staged a protest, and called for an apology for what they regarded as misleading statements by the Malaysian politicians.
After landing in Kuala Lumpur they held a news conference at a hotel holding up banners that read "We want evidence, truth, dignity" in Chinese, and "Hand us the murderer. Give us our relatives," in English.
Their designated representative, Jiang Hui, says they want the Malaysian government to apologise for the initial handling of the disaster, as well as for Prime Minister Najib Razak's earlier statement that indicated the plane had crashed with no survivors. He says the conclusion was announced "without direct evidence or a sense of responsibility".