Passenger tried to enter the cockpit on Malaysia Airlines flight

(CNN) -- Australian police have defended their actions after a passenger tried to force his way into the cockpit on a Malaysia Airlines flight from Melbourne to Kuala Lumpur Thursday.

Just after a takeoff, a male passenger on Flight MH128 tried to enter the cockpit while holding what one passenger described as a "huge, unusual, black, metallic, strange thing... size of a watermelon."

"He was yelling 'I need to see the pilot, I need to see the pilot,'" former AFL player Andrew Leoncelli told Australia's ABC News.

The mid-flight scare ended safely, but passengers later criticized the police response which saw them sit on the tarmac for 90 minutes with what they thought could be a bomb on board, according to the Australian Broadcasting Authority.

"We could see them [the police] all outside, but they weren't coming on the plane and nobody knew why," passenger Selena Brown told the ABC.

During a press briefing Thursday, Chief Commissioner of Victoria Police Graham Ashton said police initially treated the incident as terror related.

"Counter-terrorism response and protocols kicked in... for us that meant having the plane isolated, and as soon as practicable, getting the passengers off the plane safely and dealing with the offender," Ashton said.

Ashton confirmed the passenger approached the flight deck with something many feared could be a bomb.

"He was certainly at the cockpit door, seeking entry to the door, holding this device," he said. "The device was described as an amplifier type instrument... it can potentially be wired up and dealt with in a dangerous manner."

The man had recently been released from psychiatric care and was not considered a terror suspect, police said.

After flight staff intercepted the man, he was subdued by other passengers, Ashton said. "He was essentially trussed up as the flight returned to Melbourne."

Malaysia Airlines confirmed the flight was forced to turn back to Melbourne due to a "disruptive passenger."

"An investigation led by Australian authorities is currently underway and Malaysia Airlines wishes to extend its appreciation to everyone involved during the emergency situation," it said in a statement.