Washington: The FBI has released new age-progressed images of four suspected hijackers of a Pan Am flight in Pakistan, over 31 years after the crime in which 20 people, including Indian flight attendant Neerja Bhanot, were killed.

Chandigarh-born Neerja was the senior flight purser on Pan Am Flight 73, hijacked in Karachi in 1986. She was killed while helping passengers escape through emergency exits when the hijackers opened fire and set off explosives.

Neerja's bravery was portrayed by Sonam Kapoor in a 2016 critically and popularly acclaimed film of the same name.

Using age-progression technology, FBI technicians have created new photos of the four wanted hijackers.

The bureau hopes the updated images, created using Adobe Photoshop to show what the men might look like now, will generate new leads and encourage anyone with information to contact the FBI directly or submit a tip-off online.

The four suspects, listed on the FBI's "Most Wanted Terrorists" page, are Wadoud Muhammad Hafiz al-Turki, Jamal Saeed Abdul Rahim, Muhammad Abdullah Khalil Hussain ar-Rahayyal and Muhammad Ahmed al-Munawar.

They were allegedly part of the Abu Nidal Organisation, which was once considered a foreign terrorist group by the US state department, the FBI said. "The FBI has worked tirelessly over the past 31 years to bring the perpetrators of the horrific 1986 hijacking aboard Pan Am flight 73 to justice," said Andrew W. Vale, assistant director in charge of the FBI's Washington DC field office.

"The use of aged-progressed photographs is just one investigative technique the FBI is utilising to accomplish this mission."

The hijacking had taken place on September 5, 1986, when a group of terrorists led by Zaid Hassan Abd Latif Safarini seized control of Flight 73. The hijackers were eventually captured by Pakistan commandos. Safarini was sentenced to 160 years in jail in 2004. But the four wanted hijackers remain at large.

For Neerja's bravery, the Indian government posthumously honoured her with the Ashoka Chakra, the country's highest peace-time gallantry award. PTI