An Australian navy ship Ocean Shield has picked up signals “consistent” with Malaysia Airlines flight 370’s flight recorders, Angus Houston, the former Australian defense chief leading international search team, said at a press conference Monday.

“The towed pinger locator deployed from the Australian defence vessel Ocean Shield has detected signals consistent with those emitted by aircraft black boxes,” he said.

The Australian vessels detected two signals when it was located in the north of the search area. The first signal was two hours long, the second one lasted for 13 minutes.

Houston underlined that there is no confirmation yet that the signal originated from the missing Boeing’s black boxes.

“We have to produce proof in the form of plane wreckage,” he said adding that no other devices aside from flight recorders can emit fixed frequency signals.

Chinese patrol ship Haixun 01 picked up a pulse signal with a frequency of 37.5kHz per second in a new search area of missing Boeing 777 in the southern Indian Ocean on Saturday.

Malaysian passenger jet MH370 from Kuala Lumpur to Beijing vanished on March 8. There were 227 passengers and 12 crew members on board.