A British navy submarine has arrived in the southern Indian Ocean to help in the search for the missing Malaysia Airlines flight.
The vessel has 130 crew on board, and advanced sonar detection - which it's hoped could help find the aircraft's black box.
Meanwhile, Chinese relatives of the passengers have attended a private briefing in Kuala Lumpur with the Malaysian government and the airline.
Australian Prime Minister Tony Abbott says the search effort - off the western coast of Perth - will continue for as long as possible:
