COLMAR, France (Reuters) – A French appeals court on Thursday said it had refused the extradition to Serbia of former Kosovo prime minister Ramush Haradinaj, who was a guerrilla commander during the 1998-99 Kosovo war.

The court released him with immediate effect.

Authorities had earlier detained Haradinaj as he flew into France on Jan. 4 following a request from Serbia, which says he is a war criminal for his role in leading a guerrilla insurgency in its former southern province of Kosovo.

The arrest has further strained brittle diplomatic ties between Serbia and Kosovo, which declared independence with Western backing in 2008 and has demanded Belgrade drop its efforts to prosecute people linked to the conflict.

(Corrects to show court has refused extradition, not authorised it.)

(Reporting by Gilbert Reilhac; Writing by Sudip Kar-Gupta; Editing by Andrew Callus and John Stonestreet)