A Chinese patrol ship, searching for the missing Malaysia Airlines plane in the southern Indian Ocean, has detected a pulse signal on Saturday.
The ship Haixun 01 has picked up a pulse signal with a frequency of 37.5kHz per second in southern Indian Ocean waters, the state-run Xinhua news agency said.
A black box detector deployed by the Haixun 01 picked up the signal at around 25 degrees south latitude and 101 degrees east longtitude, the report said.
However, it is yet to be established whether it is related to the missing jet.
Dozens of ships and planes have joined the search, with the operation moving into its most intensive phase before batteries on the data recorders fade.
The flight is believed to have crashed in the southern Indian Ocean, although no confirmed debris has been found.
It is still not known why the plane diverted from its planned flight path from Kuala Lumpur to Beijing four weeks ago with 239 people on board.