Any data that is eventually recovered from the "black box" of missing flight MH370 will be publicly released, Malaysia's transport minister pledged Tuesday, as the government battles widespread criticism over the transparency of its investigation.

"It's about finding the truth. And when we... find out the truth, definitely we have to reveal what's in the black box," Hishammuddin Hussein told reporters.

"So there is no question of it not being released."

The government has been tight-lipped about its continuing investigation into the disappearance of the Malaysia Airlines jet, adding to the anger and frustration of relatives of the 239 people aboard the plane.

The Boeing 777 vanished on March 8 en route from Kuala Lumpur to Beijing and is now believed to have crashed in the Indian Ocean, where an Australian-led effort is under way to recover its flight data and cockpit voice recorders.

Malaysia's government has come under fire for a seemingly chaotic initial response, while the scarcity of official information on MH370 has prompted questions over its transparency.

Hishammuddin said at the weekend that Malaysia's attorney general had been sent abroad to confer with the International Civil Aviation Organization (ICAO) and determine which country will have custody of the plane's black box, if it is ever found.

But he shrugged off the importance of the custody issue on Tuesday.

"I don't think it's important who gets custody as far as I'm concerned," he told reporters.

Opposition politicians have repeatedly called for more transparency on MH370, complaining that the ruling Barisan Nasional (National Front) coalition has declined to share information with its bitter foes in the parliamentary opposition.

Corruption-prone Barisan has a history of sweeping scandals or other politically embarrassing information under the rug.

A survey released Monday showed that 54 percent of Malaysians believe the government is hiding information about MH370, while 20 percent were unsure.

Only 26 percent of the more than 1,000 people surveyed by Malaysia's leading independent polling firm said the government was being transparent, according to the news portal Malaysian Insider, which commissioned the poll.

Malaysian authorities insist they are hiding nothing but need to be cautious on commenting on ongoing investigations, and confirm information before it is released.