KUALA LUMPUR, March 31 — The Malaysian government has a contingency plan should missing Malaysia Airlines flight MH370 never be located, Acting Transport Minister Datuk Seri Hishammuddin Hussein confirmed today.

But Hishammuddin declined to reveal any details of such plans, saying it would be unfair to the families of the 239 people on board the plane that went missing on March 8.

“We have discussed it, but I think to be fair to the families, that is something we will not share at this moment because our focus is to find the aircraft,” he told reporters at the Putra World Trade Centre (PWTC) here.

He was responding to questions on whether a “backup plan” existed in the event that no debris linked to the missing plane is found.

With the multinational search already in its fourth week, several items were recovered in the Indian Ocean over the weekend but none of it belonged to the missing Boeing 777-200ER.

Hishammuddin also declined today to disclose what moves would be taken if the search exceeds 30 days, when the batteries of the plane’s “black boxes” are expected to wear out.

“What happens after 30 days expires has also been discussed and I don’t think this is an appropriate press conference to reveal that,” said Hishammuddin, who is also the defence minister.

Last week, Hishammuddin said in a daily press conference on the missing MH370 that the search operation might start using deep-sea search and salvage methods after the end of the 30-day period.

Today, he explained that the decision to use the towed pinger locator — a piece of equipment that can detect signals emitted by the black boxes as long as they are still transmitting — was made on the advice of the team involved in finding the crashed Air France flight 447.

According to Hishammuddin, the ADV Ocean Shield ship — fitted with the US’s towed pinger locator and a Bluefin 21 autonomous underwater vehicle — is expected to arrive in the search area on April 3.

This will give searchers approximately five days before the signal from the “black boxes” are set to go silent.

The minister had repeatedly stressed the importance of finding the MH370’s black boxes — its flight data and cockpit voice recorders — to help to unravel the mystery over the plane’s fate.

But with the plane missing since March 8, the black boxes are expected to stop sending out signals in seven days’ time.

This would further complicate a multinational search which has already been hampered by bad weather in recent days.

The search for the plane is now converged on a remote location in the southern Indian Ocean west of Perth, after Malaysia announced on March 24 that satellite data showed the flight “ended somewhere” in the waters there.