The Malaysian transport minister has vowed to take action against an air traffic control supervisor if it is confirmed that he was sleeping on the job when Malaysia Airlines Flight 370 disappeared a year ago.
An interim investigation report released last Sunday published transcripts of conversation between an airline official and a Kuala Lumpur air traffic controller.
Nearly four hours after the Boeing 777 with 239 people aboard dropped off radar while flying from Kuala Lumpur to Beijing on March 8 last year, the controller said he would need to wake up his supervisor to confirm details of the plane's location.
Transport minister Liow Tiong Lai said today that his department is conducting an internal probe and action would be taken if there was any misconduct.
Mr Liow said: "The work is on rotation... If he is on a working shift, this is serious. We will definitely take action if there is any misconduct."
He added that the ministry did not investigate the matter earlier as they were waiting for Sunday's report by the independent safety investigation team.
The ministry's probe will be "very fast", he added, without saying when it would be completed.
Despite an exhaustive search in the southern Indian Ocean where the plane was believed to have crashed based on analyses of transmissions between the aircraft and a satellite, no trace of wreckage has been found.
In late January, Malaysia's government formally declared the plane's disappearance an accident and said all those on board were presumed dead.
The report released on Sunday also showed the battery of the underwater locator beacon for the plane's data recorder had expired more than a year before the jet vanished, but because of a computer data error it went unnoticed by maintenance crews.
Australian Prime Minister Tony Abbott has said the hunt for the plane will continue even if searchers scouring a 23,000sq mile area of the seabed off Australia's west coast do not find it by May.
Mr Liow said a tripartite meeting involving ministers from Australia, Malaysia and China - where most of the passengers were from - would take place in Kuala Lumpur next month to discuss the next step.