A heroic Scot has told of how he tackled a passenger on a Malaysia Airlines flight after he threatened to detonate a bomb. 

Flight 128 to Kuala Lumpur, Malaysia, was forced to return to an Australian airport after a 25-year-old Sri Lankan man began shouting on board.

The incident sparked fears on board after passengers claimed to have seen an electronic device in his hand as he tried to storm the cockpit. 

Scot Robert MacDonald, was among a group of passengers who subdued the man and tied him up with belts.

Glasgow Times:

"I heard an air hostess shouting 'this guy's crazy' and there was a commotion in the seat in front of me.

"We pushed the guy onto the floor and cabin crew put cords on him and secured him to the ground.", he told the Sydney Herald.

The Scot dismissed claims he was a hero and said he wouldn't hesitate to do it again. 

"It was just my instinct to get up and help," he said.

"There were three or four guys on him already.

"He was really struggling but they were big guys so he had no chance."

"I'd do it again."

The 25-year-old had been charged from a Melbourne psychiatric hospital on Wednesday and is due to appear in court on Thursday on charges related to endangering a plane or making a false threat.

Police superintendent Tony Langdon said the flight crew also played a part in tackling the man.

"We believe that the actions of the passengers and crew were quite heroic," he said.

Passengers were kept on the plane for 90 minutes after landing and the aircraft was searche for explosives on board.

It is not believed to have been a terrorism-related incident. 

The airline said the incident would be investigated.