Chief Commissioner Martin Dolan said the new search area will be announced by ATSB Wednesday, Xinhua reported.
Dolan said earlier that the new search area would be hundreds of kilometre south of where the first phase of underwater search was covered.
Autonomous Underwater Vehicle Bluefin-21 searched some 850 sq.km of ocean floor in an area 1,600 km off the coast of Western Australia.
The area was defined on the basis of the four acoustic signals detected by the Towed Pinger Locator deployed on Australian defence vessel Ocean Shield.
Since Bluefin-21 had found neither the "black box" nor any debris of the aircraft after searching for more than 40 days. The Joint Agency of Coordination Center (JACC) for the search of the MH370 announced May 29 that area can be discounted as the final resting place of MH370, which disappeared March 8 carrying 239 people.
Earlier this month, a commercial ship, Fugro Equator, joined Chinese ship Zhu Kezhen to conduct a bathymetric survey -- mapping of the sea floor -- on an arc area of 60,000 sq. km, which was defined based on seventh arc where the aircraft last communicated with satellite.
The survey is expected to take three months.
The ATSB has also invited organisations to submit proposals to conduct the underwater search through a request for tender process. Companies can hand in submissions by June 30, 2014.
The underwater search is expected to begin in August and may take 12 months to finish.