Australian Prime Minister Tony Abbott said Friday he was "very confident" that signals detected in the search for missing Malaysia Airlines Flight MH370 were from the aircraft's black box.
"We have very much narrowed down the search area and we are very confident that the signals that we are detecting are from the black box," Abbott said from China.
Australia has been leading the search for the Boeing 777 aircraft, which went missing on March 8 en route from Kuala Lumpur to Beijing, ever since the operation was moved to the Indian Ocean.
More than 100 flights over the remote area off western Australia have so far failed to return a single piece of debris from the plane, but four signals or "pings" linked to aircraft beacons have been detected by an Australian ship.
The first two of these, which were picked up by the Australian vessel Ocean Shield using US equipment, have been analysed as being consistent with those from black box data recorders.
Speaking in Shanghai, Abbott said the search area had now been "very much narrowed down because we've now had a series of detections, some for quite a long period of time".
"Nevertheless, we're getting to the stage where the signal from what we are very confident is the black box is starting to fade," he said.
"We are hoping to get as much information as we can before the signal finally expires."
Abbott said he did not want to go into any further detail until he had briefed Chinese President Xi Jinping on the investigation. Some two-thirds of the 239 people onboard Flight MH370 were Chinese.
But he did elaborate on his confidence.
"We are confident that we know the position of the black box flight recorder to within some kilometres.
"But confidence in the approximate position of the black box is not the same as recovering wreckage from almost 4.5 kilometres beneath the sea or finally determining all that happened on that flight."
Abbott also offered support for Chinese relatives mourning loved ones lost in the tragedy.
"I grieve with all the bereaved, especially the family and friends of the 154 Chinese victims, and I offer them the assurance that Australia will not rest until we have done everything we can to provide comfort and closure," he said.