A businessman has been jailed for life for a mid-air stunt in which he faked a hijacking threat that forced the plane to make an emergency landing.

Birju Kishor Salla, from Mumbai, was arrested and charged for posing a threat to the safety of passengers and crew on board the 2017 flight from Mumbai to New Delhi on now-defunct airline Jet Airways.

A court in India heard Salla left a note in a tissue box warning of non-existent explosives on the aircraft, the country’s National Investigation Agency (NIA) said in a statement.

A female flight attendant “found a threat note in the washroom of the business class of the plane which stated that, ‘There are hijackers on board and explosives on the plane’,” the NIA said.

“Flight No. 9W 339 is covered by hijackers and aircraft should not be land and flown straight to POK,” Salla wrote in the note. POK referred to the disputed Pakistan-occupied region in Kashmir.

After being shown the note, the captain’s “face tightened”, but he quickly worked towards a safe emergency landing “without causing panic among passengers”, the Mumbai Mirror reported.

“An incident of this kind had never happened to me,” the captain, Jay Jariwala, said.

“There are guidelines we have to follow when there is any incident involving the safety of the aircraft, the passengers and the crew. We just followed procedures.

“We couldn’t let the passengers know about the specific threat, We only announced that for security reasons we were diverting the fight to Ahmedabad.”

Salla, a diamond trader, initially walked free from the flight, but authorities traced the note to him last year, and he was charged with attempting to seize control of an aircraft and for making threats.

As well as being sentenced to life in prison, Salla was fined 50 million rupees ($A1 million), which a special court ruled would be given as compensation to crew and passengers for their “misery”, the NIA said.

“Even though Salla did not actually commit the act of hijacking, that he intentionally planted a letter threatening that 12 hijackers, one of them being himself, were on board and that there were explosives in the cargo area, qualifies as a hijack threat and attempt,” an NIA official told the Times of India.

“He was masquerading as a hijacker. The conviction and life sentence should serve as a major deterrent to those who indulge in such hijack scares for the heck of it.”

The case was one of the first registered under India’s anti-hijacking law that was passed in 2016.

The law imposed stronger sentences, including the death penalty, for hijacking as well as attempts or threats to hijack.

The last hijacking of an Indian flight was in 1999 when a plane from Nepal was diverted to Afghanistan by five terrorists, CNN reported.

The 190 passengers and crew were released after the Indian government released three militants.