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 says.

Liow Tiong Lai told reporters on the eve of the anniversary of the plane’s disappearance he remained cautiously optimistic the Boeing 777 should be in the area of the southern Indian Ocean where the search has been ongoing.

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On January 29, the Malaysia government formally declared the disappearance an accident and said all 239 people on board the flight from Kuala Lumpur to Beijing were presumed dead.

Lai said Australia, Malaysia and China were due to meet in April to discuss the search effort.

“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.

“We rely on the expert group … to come up with the plan. I am cautiously optimistic it should be in this area.”

He said ships looking for debris off the coast of Western Australia had scoured more than 40 per cent of the 60,000 sqkm target area.

In the latest report Lai received on Friday, the search team identified 10 hard objects that were still to be analysed.

Such findings, which often include rubbish and cargo containers from passing ships, have been common and no trace of wreckage has been found.

Australian Transport Minister Warren Truss said last week that if the plane was not found by May, one option was to expand the hunt beyond the search zone into the wider surrounding area.

Lai said an interim report on the investigation – a requirement under international civil aviation regulations – would be presented to the Malaysian government on Saturday and released to the public on Sunday.

He outlined measures his government has already undertaken a year since the disaster, including plans to upgrade its 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 the previous 30-40 minutes.

Lai said the radar upgrade had been in the works before MH370 disappeared.

The plane dropped off civilian radar when its transponder and other equipment were switched off shortly after take-off from Kuala Lumpur, but was tracked for some time by Malaysia’s military radar as it headed south across the country towards the Indian Ocean.