CANBERRA -- Australian authorities have identified a large area in the Indian Ocean where they will focus the search for a capsized Chinese fishing vessel.

A spokesperson for the Australian Maritime Safety Authority (AMSA) told Xinhua on Thursday that, based on drift modeling, a remote 12,000 square km zone has been identified to search for the vessel.

A Chinese deep-sea fishing vessel capsized on Tuesday in the central Indian Ocean, which has so far left 39 people on board missing, including 17 Chinese mariners, 17 Indonesian mariners and five Philippine mariners.

China's Ministry of Agriculture and Rural Affairs, the Ministry of Transport, and Shandong Province have activated emergency response mechanisms to organize the rescue work. On-site rescue is underway.

An AMSA spokesperson said on Thursday that they continued to coordinate a multinational search effort after a distress beacon signal was received by AMSA from the fishing vessel at about 5:30 am (AEST) on the morning of May 16.

AMSA requested assistance from the Australian Defence Force (ADF). An ADF P-8A Poseidon aircraft was tasked with assisting with the long-range search. The ADF aircraft will re-join the search on Thursday after overnighting in the Maldives.

A private charter aircraft from Perth, the capital city of Western Australia (WA), with State Emergency Service (SES) observers on board, also assisted with the search on Wednesday and will re-join the search on Thursday.

"A number of merchant ships and other vessels have been assisting with the search and will continue to do so today. AMSA would like to thank these vessels and their crews for their invaluable assistance," the spokesperson said on Thursday.

"Australia has been liaising with the Chinese Maritime Rescue Coordination Centre (MRCC), with three Chinese naval ships continuing the search in the area today."

They said weather conditions have calmed significantly since Tuesday.