Search crews are sending a submarine into the Indian Ocean to determine whether sounds detected by equipment on an Australian ship are coming from a missing Malaysia Airlines plane, Australia's acting prime minister has said.

Warren Truss said that the crew on board the Ocean Shield ship will launch a Bluefin 21 autonomous sub on Tuesday to look for signs of flight MH370.

The latest search attempt comes a month since the Malaysia Airlines jet disappeared while flying from Kuala Lumpur to Beijing. Family members of passengers on the missing plane held vigils to mark the anniversary and are still waiting for answers.

The Ocean Shield, which is towing sophisticated US Navy listening equipment, detected late Saturday and early Sunday two distinct, long-lasting sounds underwater that are consistent with the pings from an aircraft's black boxes - the flight data and cockpit voice recorders.

The first detection held for 2.5 hours before the ship lost contact. But after turning around, the ship picked up the signal for around 13 minutes.

The boxes, thought be to lying on the ocean floor, are equipped with locator beacons that send pings, but the beacons' batteries are thought to be running out of charge.

The submarine vehicle, being deployed on Tuesday, can create a sonar map of the area to chart any debris on the ocean floor. If the sub maps out a search field, the crew will then replace the sonar system with a camera unit to photograph the debris.

Crews have been trying to relocate the sounds to determine whether they are from MH370.

"Today is another critical day as we try and reconnect with the signals that perhaps have been emanating from the black box flight recorder of the MH370," said Angus Houston, who is leading the search.

"The connections two days ago were obviously a time of great hope that there had been a significant breakthrough and it was disappointing that we were unable to repeat that experience yesterday."

Source: AP