English Premiership champions Chelsea are facing the threat of legal action over their alleged refusal to send a Nigerian teenager back to Norway.
Emmanuel Sarki has been training with the London club since the end of last year but is contracted to Lyn Oslo for three years.
Lyn Oslo's Director of Football, Morgan Andersen, told the London Evening Standard newspaper that they are anxious for Sarki to return to Oslo.
"Emmanuel Sarki is our player and we want him back. We've wanted him for a while now but Chelsea refuse to send him back," Andersen said.
He went on: "He should have been in Oslo in January. We've been communicating with Chelsea for several months and this is a situation we cannot accept.
"Emmanuel is training with Chelsea, which is great for his development, but he's registered to our club. Every club has to accept the transfer rules and regulations of players.
"Our lawyer has sent a fax to Chelsea, asking them kindly to send him back. We've been promised before that he's on his way but it's not happened. Hopefully they will follow the rules and send him back."
Sarki is a close friend and team-mate of Manchester United's new Nigerian signing John Obi Mikel.