Kuala Lumpur, Malaysia: The head of Malaysia's civil aviation regulator resigned on Tuesday after an official report found failings in air traffic control when Flight MH370 disappeared.

In a long-awaited report released on Monday, the official investigation team pointed to numerous lapses by air traffic controllers in both Malaysia and Vietnam.

These included failing to initiate "emergency phases" as required after the flight from Kuala Lumpur to Beijing with 239 people on board vanished from radar displays.

Azharuddin Abdul Rahman, director-general of the Department of Civil Aviation, said the report had found that the air traffic control did not comply with standard operating procedures.

"Therefore, it is with regret and after much thought and contemplation that I have decided to resign as the chairman of Civil Aviation Authority of Malaysia effective fourteen (14) days from the date of the resignation notice which I have served today," he said in a statement.

Flight MH370 vanished over four years ago and remains aviation's greatest mystery.

The disappearance of the Boeing 777-200 triggered the largest hunt in aviation history. But no sign of it was found in a 120,000-square kilometre Indian Ocean search zone.

In a 495-page report, investigators said they still do not know why the plane vanished.

They said the course of the Malaysia Airlines aircraft had been changed manually, and refused to rule out that someone other than the pilots had diverted the jet.

Transport Minister Anthony Loke insisted Monday that "the aspiration to locate MH370 has not been abandoned and vowed to "take action" against any misconduct committed based on the findings.