Investigators suspect Flight MH370, which took off from Kuala Lumpur for Beijing shortly after midnight on March 8, was deliberately diverted thousands of miles from its scheduled path. They say they are focusing on hijacking or sabotage but have not ruled out technical problems.
The search for the plane also continues in other regions, including a wide arc sweeping northward from Laos to Kazakhstan.
In the Indian Ocean, three Australian and two Japanese P-3 Orions joined a high-tech U.S. Navy P-8 Poseidon and a civilian Bombardier Global Express jet to search the 23,000 square km (8,900 sq mile) zone, Australian and Malaysian authorities said.
A Norwegian merchant ship, the Hoegh St. Petersburg, was diverted to the area on Thursday and another vessel would arrive later on Friday.
An Australian navy ship was expected to arrive in the search area on Saturday and Britain's HMS Echo, a multi-purpose ocean survey vessel, was also heading to the region, Malaysia said.
China's icebreaker for Antarctic research, Xuelong, or Snow Dragon, will set off from Perth to search the area, Chinese state news
(Read more: Investigators conclude flight MH370 was hijacked)