MH370: Long undersea search could cost nearly quarter billion dollars, official says

(CNN) -- A prolonged undersea search for the Malaysian jetliner could cost nearly a quarter billion U.S. dollars if private companies are used, Australia's top transport official said Thursday.

Martin Dolan emphasized that the $234 million price tag is a "ballpark rough estimate" of an extended search and salvage mission.

Searchers seem to be preparing for the possibility that an underwater drone scan of the southern Indian Ocean may not yield immediate debris from Malaysia Airlines Flight 370.

If no traces of MH370 are found, officials will be forced to review the operation and find a way forward, the Malaysian acting transport minister said Thursday.

"There'll come a time when we need to regroup and reconsider," Hishammuddin Hussein said. "But in any event, the search will always continue. It's just a matter of approach."

A later phase could involve a search along a large portion of sea highlighted by a partial digital "handsh