Malaysian Minister of Transport Liow Tiong Lai gestures during an interview with Reuters ahead of the one-year anniversary of the disappearance of Malaysia Airlines flight MH370, in Putrajaya, March 6, 2015. [Photo/Agencies]

KUALA LUMPUR - If the massive undersea search for Malaysia Airlines Flight 370 turns up nothing by the end of May, the three countries leading the effort will return to the drawing board, Malaysia's transport minister said Saturday.

Liow Tiong Lai told a small group of foreign reporters on the eve of the anniversary of the plane's disappearance that he remains cautiously optimistic the Boeing 777 is in the area of the southern Indian Ocean where the search is ongoing.

Despite the exhaustive search for the plane, which disappeared last March 8 during a flight from Kuala Lumpur to Beijing, no trace of the jet has been found. Malaysia's government on Jan. 29 formally declared the incident an accident and said all 239 people on board were presumed dead.

"By the end of May, if we still can't find the plane, then we will have to go back to the drawing board," Liow said.

Asked if Malaysia might stop the search if there are no new leads by the end of May, when bad weather usually sets in, Liow said it was "too early to pre-empt anything now," and that the government would continue to rely on the group of experts leading the hunt.

"We stand guided by the expert team," he said.

"I am cautiously optimistic it should be in this area," he said, adding that "we need directions, we need plans, we need to review all the data that we have."

Liow said that Australia, Malaysia and China would meet next month to discuss the next steps in the search.