A Swedish appeals court has rejected Tesla's (TSLA.O) attempt to force postal firm PostNord to deliver licence plates to the U.S. automaker, according to a ruling made on Thursday, part of a wider battle between the car company and labour unions.

A district court had ruled earlier in December that PostNord for the time being does not need to deliver licence plates to Tesla, which is being blocked by the postal service's workers as part of a sympathy strike.

But while the postal blockade makes access to licence plates more difficult, Swedish media has reported that the company has found ways to circumvent the unions by asking car buyers to order plates themselves.

Tesla is facing a wave of union action in the Nordic region, backing Swedish IF Metall's mechanics who went on strike in October, demanding a collective agreement covering wages and other conditions.

"It is gratifying that the court of appeal reached the only reasonable conclusion, that the constitutionally protected right to strike takes precedence over Tesla's interests," labour union Seko's president Gabriella Lavecchia told Reuters by email.