Australia's prime minister says the search for Malaysia Airlines Flight 370 is "an extraordinarily difficult exercise" but that it will go on as long as possible.
Tony Abbott said Monday that although no debris has been found in the southern Indian Ocean that can be linked to the plane missing for more than three weeks, the searchers are "well, well short" of any point where they would scale the hunt back.
Abbott says the best brains in the world are applying themselves to this task and adds: "If this mystery is solvable, we will solve it."
Dozens of Chinese relatives of passengers on Flight MH370 arrived in Malaysia early Sunday, telling reporters they wanted proof from Malaysian authorities that the aircraft — missing for more than three weeks — crashed in the Indian Ocean.
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A spokesman for the 35-person group also demanded the Malaysian government apologize for "giving out confusing information," which he said caused a delay in the search and rescue effort.
Members of the group, gathered at The Holiday Villa in the city of Subang Jaya, 20 kilometres from the capital Kuala Lumpur, held banners that read, "We want evidence, truth, dignity" in Chinese, and "Hand us the murderer. Tell us the truth." A slogan in English read, " You must return relatives."
Two-thirds of the 227 passengers aboard the plane, which disappeared en route to Beijing from Kuala Lumpur on March 8, were Chinese, and China has urged Malaysia to be more open about the investigation.
One of the relatives, who gave only his surname, Xu, said they want to meet officials "at the very highest levels."
But a representative of the group said they have no desire to head to Australia just yet, although the search operation is centred there.
"I have not heard of any families wanting to head to Australia — because we, the families, based on our feelings and the actual evidence, without any direct evidence we will not want to head there," said Jiang Hui.
"I think everyone is more rational now, more rational," he added when reporters asked what is the emotion state with the families now.
The search continued on Sunday, with 10 ships and as many aircraft combing the new search area, 1,850 kilometres west of Perth.
Numerous objects have been spotted in the two days since Australian authorities moved the search 1,100 kilometres northeast after new analysis of radar and satellite data concluded the Boeing 777 travelled faster and for a shorter distance after vanishing from civilian radar screens.
However, none has been confirmed as coming from Flight MH370.
An Australian warship with an aircraft black box detector departed Sunday to join the search. The equipment can detect transmissions from the plane's black box, even at a depth of 6,000 metres, but it could take three to four days for the ship, the Ocean Shield, to reach the search zone, an area roughly the size of Poland.
The batteries on the recorders allow transmission for about 30 days.
Much of the sea floor in the search area is about 2,000 metres below the surface, but depths may reach a maximum of up to 6,000 metres.
About 252,000 square kilometres of ocean were covered in the search on Sunday, said the Australian Maritime Safety Authority said. Nine planes and nine ships scanned the ocean.
Lt. Russell Adams of the Australian air force said his crew saw at least four objects, orange in colour and bigger than two metres, in size before the day's search operation ended. None of the objects has been verified as being plane wreckage.