Newcastle United have rejected a £1.5 million bid for Fraser Forster from Celtic.
The 23-year-old spent last season on-loan at Celtic Park as Neil Lennon's side finish second behind eventual SPL champions Rangers.
Forster, who has never made an appearances for Newcastle since joining as a trainee in 2006, has spent spells out on loan at Norwich City, Bristol Rovers and Stockport County and was expected to make a permanent move to Celtic this summer.
"We have made a bid for Fraser Forster," Lennon confirmed.
"Newcastle have said that he is not for sale at the moment but we will pursue that avenue further if we can."
However, upon his return, Alan Pardew said he thought little of Forster's stay at Celtic.
"We've been disappointed with the quality of the games, other than the occasional Rangers versus Celtic game, and even some of those have been poor," he said.
With Steve Harper having turned 36 in March, and Tim Krul having failed to become No.1 at St James's Park, Forster could find himself as first choice in the Newcastle goal next season.
Celtic meanwhile are likely to return with an improved offer for Forster, while also tying Lukasz Zaluska down to a new deal.