CREWS will resume the underwater hunt for missing Malaysia Airlines Flight 370 at the end of the month.

They will begin the search in an area farther south than initially planned.

The search had been due to start next week but the first of three ships that will scour a remote patch of the Indian Ocean for the plane that vanished in March needed to undergo some additional work in Indonesia.

Australian transport safety bureau chief commissioner Martin Dolan said the ship, Malaysia's GO Phoenix, is now expected to begin searching on September 30.

Officials have been refining their analysis of satellite data from the Boeing 777 to get the best idea of where they believe it crashed into the ocean far off Australia's west coast.

Flight 370 disappeared on March 8 after veering off its northerly course from Kuala Lumpur to Beijing for reasons unknown. No trace of the aircraft or the 239 people on board have been found although the investigation has focused on the actions of the pilot.