The Edict of Milan was signed by emperors Constantine I and Licinius in 313 and announced religious tolerance in the Roman Empire.
Constantine was born in Naissus, modern day Nis.
The Vatican generally says that the Pope will visit countries which have a Catholic minority only with the consent of the majority church in the country.
If the Serbian Orthodox Church agrees to invite Pope Benedict at its annual meeting on Monday, church leaders expect that he will attend the commemoration in Nis.
Serbian Patriarch Irenj, who was previously the Bishop of Nis, stressed even before coming the leader of the SPC that a visit by the pope would help improve relations between Orthodox and Catholic Christians.
If Pope Benedict visits Serbia, it would be the first visit by a pope in years.
It remains unclear, however, whether the bishops will agree to extend an invitation to the pope.
"It's no secret that there are bishops sitting in the council who not only strongly oppose the visit but also sharpen the politics of ecumenism," the source in the SPC said.
On one hand, Serbia wants to maintain top relations with The Vatican because it has not recognised the independence of Kosovo. On the other hand, the source in the SPC said that the stance of other Orthodox churches, especially the Russian Church, plays a major role in deciding whether or not to extend an invitation.
"Some church authorities believe that head of the Serbian Orthodox Church should meet Pope Benedict only after Moscow's Patriarch Cyril meets the pope," the source added.
The idea to invite the pope to Serbia was first "pushed" by the head of a former state union of Serbia and Montenegro, Svetozar Marovic, during his visit to The Vatican in 2003.
The Council is also set to discuss the reorganisation of some dioceses, and the extradition of former bishop Artemije.
