Perth: A mini-submarine deployed to find the crashed Malaysian jet's wreckage has finally completed a full 16-hour mission in its third attempt, even as Australian Prime Minister Tony Abbott today said the underwater search may end in about a week and move to a "different phase".

Two previous missions by autonomous underwater vehicle Bluefin 21, a US Navy probe equipped with side-scan sonar, to map the Indian Ocean seabed were cut short by technical problems and deep waters without making any "significant" detections. "Overnight Bluefin-21 AUV completed a full mission in the search area and is currently planning for its next mission. Bluefin-21 has searched approximately 90 square kilometres to date and the data from its latest mission is being analysed,"

Operators aboard ADF Ocean Shield moving US Navy’s Bluefin-21 into position for deployment in the search of missing Malaysia Airlines flight MH370This handout image from the US Navy shows operators aboard ADF Ocean Shield moving US Navy’s Bluefin-21 into position for deployment in the search of missing Malaysia Airlines flight MH370. Pic/AFP

Joint Agency Coordinating Centre (JACC) that is leading the search operations said on the 41st day of the search for the Malaysia Airlines Flight MH370. The JACC also said the oil sample collected by Australian defense vessel 'Ocean Shield' had now arrived in Perth and will be subject to detailed testing and analysis.

"We will provide details of the results when they become available," JACC said. Bluefin 21 is searching in an area defined by four acoustic signals picked up by an Australian search team.

Meanwhile, Australian Prime Minister Abbott said the best leads -- the four underwater signals consistent with aircraft black boxes picked up by an Australian Navy ship -- in the underwater search for the plane Boeing 777-200 will be exhausted in about a week.

Abbott said authorities would need to rethink their approach if the remote-controlled vehicle fails to locate the plane's wreckage in a narrow area of ocean where searchers picked up a series of pings. "We believe that search will be completed within a week or so," Abbott was quoted as saying by The Wall Street Journal.

"If we don't find wreckage, we stop, we regroup, we reconsider." "My determination for Australia is that we will do whatever we reasonably can to resolve the mystery. If the current search turns up nothing, we won't abandon it, we will simply move to a different phase," he said. However, the Australian Prime Minister did not elaborate on what the new phase may be.

Meanwhile, Malaysia's Transport and Defence Minister Hishammuddin Hussein today warned that the cost of the search for the plane's wreckage will be "huge".

"When we look at salvaging (wreckage) at a depth of 4.5 kilometres, no military out there has the capacity to do it," Hishammuddin told reporters in Kuala Lumpur. "We have to look at contractors, and the cost of that will be huge," he said.

The aerial and sea search for the plane continued today with up to 10military aircraft, two civilian plane and 11 ships taking part in the operations.

The Beijing-bound plane carrying 239 people, including five Indians, an Indo-Canadian and 154 Chinese nationals - had mysteriously vanished on March 8 after taking off from Kuala Lumpur. Using satellite data, officials have concluded that it ended its journey in seas west of Perth.

They do not know why the plane flew so far off course and an investigation is ongoing. Finding the plane's flight recorders are seen as key to understanding what happened.

The Bluefin-21, operated by the US Navy off the Australian vessel Ocean Shield, is an autonomous underwater vehicle (AUV) that can identify objects by creating a sonar map of the sea floor.