Missing MH370: It's time to go underwater, says Australia official

Robotic submarine was deployeded for the first time to locate Malaysian jet after searchers failed to detect any more signals

A robotic underwater drone was today deployed for the first time to locate the crashed Malaysian jet's "final resting place" in the Indian Ocean at a depth of 4,500 metres after searchers failed to detect any signals from the plane's black boxes in a week.

The Bluefin 21, a US Navy probe equipped with side-scan sonar, was launched this evening from the Australian navy ship Ocean Shield, the Joint Agency Coordination Centre (JACC) which is leading the search said on the 38th day of the hunt for the Flight MH370 that mysteriously disappeared on March 8.

"We haven't had a single detection in six days so I guess it's time to go underwater," Australian chief search coordinator Angus Houston told a news conference.

Earlier today, he said the Ocean Shield will cease searching with the towed pinger locater and deploy the autonomous underwater vehicle as soon as possible.

In another significant development in the search, Houston said two litres of the newly spotted oil slick had been collected for testing.

"I stress the source of the oil is yet to be determined but the oil slick is approximately 5,500 metres downwind... from the vicinity of the detections picked up by the towed pinger locater on Ocean Shield," he said.

Houston said he did not think the oil slicks were from one of the many ships involved in the search but it would take a number of days before the oil could be conclusively tested.

"It's very close to where the transmissions are coming from and we'll investigate it and that will take a little bit of time, given that we're in the middle of the Indian Ocean. We don't think it's from the ships, so where is it from? So it's another lead to pursue," he said.

The underwater drone's side-scan sonar is an acoustic technology that can create a three-dimensional sonar map of any debris on the seafloor.

Multi-nation search teams used a towed pinger locater to listen for signals from the plane's black box flight recorders till now and detected four "pings" possibly from the black boxes of the plane. But no new signals have been heard since April 8, amid concerns the flight recorders' batteries have expired.

The Malaysia Airlines Flight MH370 with 239 people, including five Indians, was flying from Kuala Lumpur to Beijing when it lost contact with air traffic controllers over the South China Sea.

The search teams, armed with sophisticated naval aircraft and ships, have focused on waters west of the Australian city of Perth, with teams racing against time to detect signals before the flight recorder batteries - which last about one month - run out.