The bureau is hopeful that the images, which have been generated using Adobe Photoshop's program on January 11, are aimed at showing how the men would look like today, CNN reported.
The development is aimed at evolving new leads and encouraging the public to report any information they may have, in order to nab the culprits.
"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 assistant director in charge of the FBI's Washington, DC field office Andrew W Vale.
He added: "The use of aged-progressed photographs is just one investigative technique the FBI is utilising to accomplish this mission."
The bureau including names of all four suspects in its most wanted terrorist list in 2009 after it originally obtained their images in 2000.
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The suspects include Wadoud Muhammad Hafiz al Turki, Jamal Saeed Abdul Rahim, Muhammad Abdullah Khalil Hussain ar-Rahayyal and Muhammad Ahmed al -Munawar.
Reward
The State Department's Rewards for Justice Programme has offered a reward money of up to $5 million each for any leads that may prove useful in the arrests of the alleged hijackers.
"We have a team of agents who are committed to furthering this investigation and locating these alleged terrorists," Vale told CNN in an email.
It's been over 31 years since the 16-hour deadlock on September, 1986, when a number of terrorists commanded by Zaid Hassan Abd Latif Safarini took control of Flight 73. However, Pakistani commandos eventually captured some of the hijackers.
Safarini, who had confessed involvement in the attack and declared allegiance to the Abu Nidal Organisation (ANO) was sent behind bars for 160 years in 2004.
The four other wanted hijackers, allegedly seen in Pakistan in 2008, have been at large.
"No matter how much time has passed or the obstacles we encounter, we owe it to the victims and their families to never give up on them," said FBI special agent Terrence Mcintyre in a statement.
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