Hishammuddin said since Flight MH370, carrying 227 passengers and 12 crewmembers, disappeared Saturday, Malaysian officials have been in regular contact with neighboring countries and accepted all offers of help.
"Malaysia has nothing to hide. We have spared no expense and no effort," he said before taking questions at a news briefing in Kuala Lumpur. "We have followed protocols as stipulated by the International Civil Aviation Organization since the incident began."
"This is a crisis situation. It is a very complex operation, and it has not always been easy," he said. "We are devoting all our energies to the task at hand. And I want to be very clear: our focus has been on finding the aircraft. We have not done anything that could jeopardize the search effort."
Forty-three ships and 40 aircraft are searching the South China Sea and the Strait of Melaka for the Boeing 777-200 that went missing about an hour after departing for Beijing from Kuala Lumpur, Hishammuddin said.
"With every passing day, the task becomes more difficult," he said. "We will spare nothing in our efforts to find MH370."
He said reports that the aircraft may have kept flying after last contact were "inaccurate," and that teams from Rolls Royce, the engine maker, and Boeing were in Kuala Lumpur working with Malaysia Airlines on such matters.
"As far as Rolls Royce and Boeing are concerned, those reports are inaccurate," Hishammuddin said.
He said a Malaysian Maritime Enforcement Agency surveillance plane was sent Thursday to investigate potential debris that appeared on Chinese satellite images "but found nothing," the Bernama news agency reported.
The aircraft was fit to fly and all its maintenance checks were in order, Hishammuddin said.
"[This] situation is unprecedented," he said. "MH370 went completely silent while over the open ocean. We are in the middle of a multinational search involving many countries and more than 80 ships and aircraft."