No evidence of terrorism threat - Najib

However, Prime Minister Datuk Seri Najib Tun Razak stressed that the government will take into account any possibility that could lead to solving this incident.

"There is no proof now, all sorts of theories have been spread. We have to look at all possibilities and investigate thoroughly before a conclusion can be reached," he said.

He also said they would review the protocol used at the Kuala Lumpur International Airport (KLIA).

"We will check all the protocols to see if upgrading is necessary. With the current practice we are not able to identify the exact cause and what exactly happened," he said at a press conference after the opening ceremony of National Reunification Program in Cheras, Kuala Lumpur.