Leilua was released by the Roosters in December with two years of his contract remaining amid rumours the 21-year-old was not favoured by new coach Trent Robinson.
Until the NRL confirm a figure for next season’s salary cap however, Leilua’s deal with Newcastle has yet to be officially signed off.
“It is great we have BJ as a possible addition to our squad for season 2013,” chief executive Matt Gidley said.
“We are frustrated we can’t do anything official with him until the salary cap is confirmed, but we have BJ in our plans and hope to make it official sooner rather than later.”
Club officials also revealed that an offer has been made for Melbourne winger Anthony Quinn to make a surprise return to Newcastle.
Quinn, 29, who made over 100 appearances for the Knights between 2002 and 2006, has been training with the club but has yet to formally respond to the offer.