A Bangladeshi man shot dead after he tried to force his way into the cockpit on a Dubai-bound flight was carrying a toy gun, police revealed on Monday, contradicting an earlier statement from the army that he had fired the first shot.

Police officials said they are investigating how the “mentally imbalanced” man was able to board the Biman Bangladesh Airlines flight in Dhaka and threaten the pilot.

The Boeing 737-800 pilot was forced to make an emergency landing at Bangladesh’s Chittagong airport on Sunday. Commandos then stormed the plane and shot the would-be hijacker – who later died later of his injuries – in what the military had earlier said was an exchange of gunfire.

“The pistol with the suspect was a toy pistol and he had no bomb attached to his body,” said Kusum Dewan, additional commissioner of Chittagong police.

“He appeared to be mentally imbalanced. We heard he had a personal issue with his wife and demanded to speak to the prime minister. But we are still investigating. We don’t want to come to any conclusions right now.”

Bangladeshi security forces react to the hijacking: in pictures Show all 8 1 /8 Bangladeshi security forces react to the hijacking: in pictures Bangladeshi security forces react to the hijacking: in pictures Security forces stand guard at the Shah Amanat International Airport in Chittagong, Bangladesh after a man attempted to hijack a plane EPA Bangladeshi security forces react to the hijacking: in pictures Photo released by Bangladeshi Police of Mahmud Polash Ahmed, who was shot dead after attempting to hijack the plane with a toy gun AP Bangladeshi security forces react to the hijacking: in pictures Security personnel search a vehicle at an entrance to the airport in Dhaka, Bangladesh as security is boosted following the hijacking at Chittagong airport AFP/Getty Bangladeshi security forces react to the hijacking: in pictures Security personnel search people at an entrance to the airport in Dhaka, Bangladesh as security is boosted following the hijacking at Chittagong airport AFP/Getty Bangladeshi security forces react to the hijacking: in pictures Security personnel search a vehicle at an entrance to the airport in Dhaka, Bangladesh as security is boosted following the hijacking at Chittagong airport AFP/Getty Bangladeshi security forces react to the hijacking: in pictures Security personnel search people at an entrance to the airport in Dhaka, Bangladesh as security is boosted following the hijacking at Chittagong airport AFP/Getty Bangladeshi security forces react to the hijacking: in pictures Security personnel stand guard at an entrance to the airport in Dhaka, Bangladesh as security is boosted following the hijacking at Chittagong airport AFP/Getty Bangladeshi security forces react to the hijacking: in pictures Bangladesh civil aviation minister Mahbub Ali, center, addresses a news conference in Dhaka on Monday 25 February AP

All 148 passengers and crew were able to safely disembark before soldiers stormed the plane and ordered the suspect to surrender. The suspect was fired at after he shot at the soldiers, a military spokesman had told reporters on Sunday.

Nayeem Hasan, chairman of the Civil Aviation Authority, said it was a mystery how the man, believed to be in his 20s, had managed to board the plane with an object resembling a pistol.

“It was the responsibility of the Civil Aviation Authority to search each passenger before boarding and it was done for this aircraft also, but it is a big question to us that how he boarded with a pistol,” he said.

Bangladeshi security personnel inspect plane after exchange of gunfire with hijacker (AFP/Getty Images)

“Now we are focusing on two issues – his background and identity and the security aspect that how he boarded with a pistol.”

Politician Moin Uddin Khan Badal, on board the plane, told Bangladeshi media the man had demanded to speak to the country’s prime minister Sheikh Hasina.

The airline said the aircraft left Dhaka for Dubai at 4.35pm, and landed at Chittagong airport around 5.40pm local time.

Flights were suspended at the airport during the brief standoff with the would-be hijacker.