A Malaysia Airlines passenger tried to enter the cockpit during a flight from Melbourne to Kuala Lumpur, prompting the crew to turn back to Australia.
There were fears he was carrying a suspected detonator as witnesses claimed an “electronic frequency” device was in his hand.
Melbourne Airport was put on lockdown and incoming aircraft were diverted to Avalon Airport.
Malaysia’s Deputy Transport Minister Abdul Aziz bin Kaprawi confirmed that a passenger on board had claimed he was carrying a bomb.
He said: “One disruptive passenger tried to enter the plane’s cockpit.
“The passenger, a Sri Lankan national, claimed to have a bomb.”
Fearing for the safety of the aircraft, the pilot was forced to turn back.
The airline said Flight MH128 successfully landed at Melbourne Airport at 11.41pm local time — half an hour after takeoff.
Armed police boarded the aircraft to remove the suspect and confirmed no explosives were on board.
Dramatic photos show the suspect on the floor with his wrists bound by cable ties as staff restrained him.
A passenger who identified himself as Andy told local 3AW radio he decided to “f***ing do something” when he heard the threat.
“I said mate, what are you effing doing? And he said ‘I’m going to blow the f***ing plane up, I’m going to blow the f***ing plane up'”, Andy said.
“I approached him and he ran down the side and then he ended up going down the back of the plane.
“Then two lads grabbed him and disarmed him and mashed the crap out of him and put hog ties on him and took the giant black thing out of his hand,” he said.
The device in the man’s hand was “the size of a watermelon”, he added.
“It was huge, it was black and it had two black antennae coming off it, but it also looked like an iPhone jack. So it could have been just a beatbox thing”.
The airport began accepting arriving and departing flights from 2:30am local time (5.30pm GMT).
According to officials the incident was not a hijack and that the suspected bomb was a “powerbank.”
Saiqa Chaudhery, whose husband was on the plane, told news.com.au that the man appeared to be under the influence of drugs.
“He heard a lot of screaming and [an] airhostess calling out for help as a passenger attacked her,” Mrs Chaudhery said.
“Some other passengers and crew tied the man down and [the] flight landed back at Melbourne Airport.”