Iranian Foreign Ministry Spokesman Bahram Qassemi underlined Tehran's serious pursuit of the fate of kidnapped Shiite Cleric Imam Musa al-Sadr.
"The case of Imam Musa al-Sadr is so important for the Iranian government that it has always been on its agenda," Qassemi said on Monday.
In April 2012, Libyan Government's Spokesman Nasser al-Manee announced that a series of documents belonging to the former Libyan regime indicate that the Iranian-born Lebanese Shiite cleric has been killed by Qaddafi regime.
"Based on the information discovered in Qaddafi regime's security office, Imam Musa al-Sadr and his friends were martyred by the suppressing forces of Qaddafi," Manee told FNA at the time.
Al-Sadr, an Iranian-born Lebanese philosopher, spent many years of his life in Lebanon as a religious and political leader before he went missing during a trip to Libya at the invitation of Muammar al-Qaddafi.
In August 1978, al-Sadr departed for Libya with two companions to meet officials of Libyan leader Muammar al-Qaddafi's government. They were never heard from again, and many believe they met with foul play at the hands of Qaddafi.
The Qaddafi-ruled Libya consistently denied responsibility, claiming that al-Sadr and his companions left Libya for Italy in 1978. However, others claimed that al-Sadr was still alive and being kept in a secret jail in Libya.
Rome has persistently said that al-Sadr never arrived in Italy on the alleged flight.
While al-Sadr's family said that he was still alive and remained a prisoner in Libya, Qaddafi's former associate Abdel-Monem Houni claimed in February that al-Sadr had been killed and buried shortly after he was kidnapped.