The broadcaster is planning to move from its current premises on Ormeau Avenue but has yet to decide on a location.
The property news service, Co-Star, said land agent Lambert Smith Hampton is now advising on the relocation.
It said the Sirocco site and a site near the new Ulster University campus have "emerged as early favourites".
Co-Star said that "market sources" have suggested that the BBC's need for studio space and parking for broadcast vehicles mean it will need a development site rather than refurbished space.
Sirocco is a 16-acre site beside the river Lagan.
The Carvill Group had planned to develop a hotel, supermarket and 2,400 apartments there before the property crash.
It ultimately ended up in the control of the Cerberus investment fund which recently sold it to an unnamed buyer.
The BBC has previously been linked with a move to Titanic Quarter or as part of the redevelopment of Great Victoria Street station.
Belfast City Council has said it would like the broadcaster to move close to Ulster University.
It has said land to the rear of Belfast Central Library, a site north of Great Patrick Street or the stalled Royal Exchange development could all be suitable.
BBC Northern Ireland has been linked with a move to the Sirocco site in east Belfast.