Burnley defender Ben Gibson has been given permission to train with his former club Middlesbrough.
The 27-year-old joined the Clarets from Boro for £15m in August 2018 but has only appeared once in the league.
His sole competitive game for Burnley this season came in a 3-1 Carabao Cup defeat by Sunderland in August.
The Clarets said Gibson had "made it clear that he wanted to leave" in January but that they "did not receive an offer it felt was acceptable".
Gibson made 185 league appearances for Boro and was called up to the England squad in March 2017.
He has two years remaining on his Burnley contract.