Kenneth Omeruo believes another loan move to Middlesbrough is the best option for him at this stage of his career.
Hibernian have signed former Scotland Under-21 international Scott Allan from West Brom.
Leeds pair Ben Parker and Mika Vayrynen have had their contracts terminated by mutual consent.
Left-back Parker, 24, was the club's longest-serving player having made his debut in the Carling Cup in August 2007, while Finland international midfielder Vayrynen, 30, has made just three starts since being signed by former manager Simon Grayson last September.
Both player's respective contracts were due to expire in the summer, but an early termination has been agreed, with Parker set to train with the squad for the remainder of the season.
Parker has endured a catalogue of career-threatening setbacks since suffering a hip injury on the opening day of the season against Exeter in August 2009, under-going a series of operations to resolve back, Achilles, hamstring and groin problems.
The youth academy product has not appeared for Leeds this season, but spent a month on loan at Carlisle earlier this year.
Vayrynen, who has made 54 appearances for his country, made his Leeds debut as a substitute against Manchester United in the Carling Cup in September last year and last appeared in the FA Cup defeat at Arsenal in January.