Malaysian Prime Minister Najib Razak on Thursday joined his Australian counterpart Tony Abbott in a tour of RAAF Base Pearce, near Perth, where aircrews from seven countries have been flying dozens of missions deep into the southern Indian Ocean.
Malaysian authorities have faced heavy criticism, particularly from China, for mismanaging the search, now in its fourth fruitless week, and holding back information. Most of the 239 people on board the flight were Chinese.
"The world expects us to do our level best, and I'm very confident we will indeed show what we can do together as a group of nations; that we want to find answers, that we want to provide comfort to the families and we will not rest until answers are indeed found," Najib said.
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Authorities have not ruled out mechanical problems as causing the disappearance, but say all the evidence suggests the plane was deliberately diverted from its scheduled route.
Malaysia's police chief said the investigation was focusing on the cabin crew and pilots, after clearing all 227 passengers of possible involvement in hijacking, sabotage or having personal or psychological problems that could have been connected to the disappearance.