Manchester United manager Jose Mourinho says the club are now concerned over the possibility of losing Marouane Fellaini on a free transfer next summer with the player's contract situation out of his hands.

In January, United triggered a clause in Fellaini's contract to extend his stay at the club until 2018 but so far their attempts to agree fresh terms with the Belgium international have been fruitless.

The former Everton midfielder, signed by the club for £27.5m in 2013, has already turned down one offer with a number of clubs now beginning to circle with foreign suitors able to discuss pre-contract terms with him from 1 January.

Mourinho is keeping out of the ongoing negotiations between the board and Fellaini, leaving it up to executive vice-chairman Ed Woodward to convince the powerful midfielder to remain in Manchester.

Speaking at a press conference ahead of Saturday's Premier League clash against Brighton and Hove Albion, the United boss said: "It is a discussion between the players and the board. I am not involved in contracts, in deals.

"I respect both, the player because the player has the right to decide his future. He finishes his contract, he has the right to decide his future, and I respect the board because the decisions and the discussions are under their control. So I just wait, wishing that they will have an understanding but it is out my control."

Fellaini returned from a knee injury just before November's international break, and came on as a second-half substitute in the 4-1 win over Newcastle United last Saturday. United's injury concerns have eased somewhat recently with Paul Pogba, Zlatan Ibrahimovic and Marcos Rojo all returning from injury layoffs ahead the busy festive period with United trailing neighbours Manchester City by eight points in the Premier League.

Marouane Fellaini
Fellaini can speak to foreign clubs as of 1 July. Getty