The Republic of Ireland international spent last season on loan at Elland Road and has signed a three-year deal with the Yorkshire club.

Leeds boss Kevin Blackwell had been keen to boost his squad.

Shaun Derry is set to miss four weeks after an operation on a hernia, while Steve Stone and Kevin Nicholls are also out injured.

Douglas signed for Blackburn as a trainee in 2000 and has also had loan spells with Chesterfield, Blackpool and Gillingham.