CELTIC have been placed on alert after Rosenborg announced that Mikkel 'Mix' Diskerud, a summer transfer target for the SPFL Premiership champions, has left the club after failing to agree a new contract.

The Norwegians issued a statement on their official website last night to confirm that the United States international midfielder is now looking for fresh employment and will be available to join a new club from January 1.

Diskerud was also linked with a move to Stromsgodset during Ronny Deila's time there as head coach, and the Celtic manager will certainly have him under consideration as he endeavours to strengthen his squad for the challenges presented by a tight race for the domestic league title and a meeting with Inter Milan in the last 32 of the Europa League.

Diskerud played 78 games for Rosenborg and scored eight goals.

He is Norwegian by birth, but qualifies to play for the United States through his mother and now has 25 caps, although he failed to make the field in the World Cup finals despite making the final squad.

"Rosenborg wanted to write a new contract with Mix, but discussions with the player's representatives have not been successful," stated the Norwegian club. "Mix thus leaves Rosenborg."

Should Celtic push forward with a concrete offer, they will face competition from clubs in the States and the Mexican side, Club Tijuana.