BANGKOK, Thailand (CNN) -

Australian authorities most likely will announce the next search area for Malaysia Airlines Flight 370 on Thursday, a senior Malaysian official told CNN on condition of anonymity Wednesday.

The search area will be "refined," rather than brand new, and still will be in the southern Indian Ocean, where previous underwater explorations have failed to find the aircraft, the official said.

Flight 370 disappeared over Southeast Asia on March 8, and searchers have found no trace of the Boeing 777 or the 239 people aboard, making it one of the biggest mysteries in aviation history. The flight had been scheduled to go from Kuala Lumpur, Malaysia, to Beijing.

Officials with three nations deeply involved in the search -- Malaysia, China and Australia -- approved the next search zone, the senior Malaysian official said.

The Australian Transport Safety Bureau said this week that it's been re-examining data and that the review could shift the search area south of the previous zone.

Searchers plotted initial search areas based in part on satellite data that they said indicated the plane flew to the southern Indian Ocean. Hopes of closure then were raised in early April, when a search team detected pings west of Australia that were initially thought to have come from the plane's flight data recorders.

But Australian authorities said an exhaustive search of the sea floor around the pings yielded no wreckage and ruled the area out as the aircraft's final resting place.

Last week, a group of independent experts -- using satellite data publicly released in May -- also said it thought the missing aircraft was in the south Indian Ocean, but approximately hundreds of miles southwest of the previous search site.