Doug Marrone has admitted that he does not know whether Kevin Kolb will be returning to the Buffalo Bills in 2014.

The quarterback missed the entire 2013 campaign after sustaining a concussion in the pre-season, leading to reports that the 29-year-old was considering retirement.

The head coach told WGR-AM: "He's under contract and I'm not aware of really what exactly is going on right now, whether he's planning to come back, whether he's not going to come back. I have not been informed of anything to that nature."

Kolb joined the Bills after being released by the Arizona Cardinals last off-season.