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 re-examine data and come up with a new plan, Malaysia's transport minister said Saturday.

Liow Tiong Lai told a select group of foreign reporters on the eve of the anniversary of the plane's disappearance during a flight from Kuala Lumpur to Beijing that he remains cautiously optimistic that the Boeing 777 should be in the area of the southern Indian Ocean where the search has been ongoing.

Malaysia's government on Jan. 29 formally declared the plane an accident and said all 239 people on board were presumed dead.

Lai said that Australia, Malaysia and China were due to meet next month to discuss the search efforts.

"By the end of May, if we still can't find the plane, then we will have to go back to the drawing board," he said in the interview. "We rely on the expert group ... to come up with the plan. I am cautiously optimistic it should be in this area."

He said "we need directions, we need plans, we need to review all the data that we have" under experts' guidance.

He said that ships looking for debris from the plane at the ocean floor off the coast of western Australia have so far scoured more than 40 percent of the 60,000 square kilometers (23,166 square miles) area where the search has been focused on. In the latest report he received Friday, he said the search team identified 10 hard objects which are still to be analyzed.

Such findings, which often include trash and cargo containers from passing ships, have been common and so far no trace of wreckage has been located.

Australian Transport Minister Warren Truss said last week that if the plane isn't found by May, one option is to expand the hunt beyond the current search zone into a wider area surrounding it.

Australia's Prime Minister Toby Abbott said Thursday "I can't promise that the search will go on at this intensity forever," but added "we will continue our very best efforts to resolve this mystery and provide some answers."

Lai said an interim report on the investigation — a requirement under international civil aviation regulations — will be presented to the Malaysian government on Saturday and released to the public on Sunday. He didn't comment on it.

But he outlined measures his government has already undertaken a year since the disaster, including plans to upgrade radar system to cope with bigger traffic volume and a new tracking system on Malaysia Airlines flights that sends aircraft data every 15 minutes, instead of previous 30 to 40 minutes.

He said that the radar upgrade had been in the works even before Flight 370 disappeared. The plane dropped off civilian radar when its transponder and other equipment were switched off shortly after takeoff from Kuala Lumpur but was tracked for some time by Malaysia's military radar as it headed south across the country toward the Indian Ocean.