French Top 14 club Lyon announced on Monday they are taking legal action against Franco Mostert for breach of contract.

The Lions and Springbok lock signed a two-year deal with Lyon, which was announced in March, and he was supposed to join the club at the end of the Rugby Championship. Mostert failed to report for duty and has instead moved to the Ricoh Black Rams in Japan, with the aim of returning to the Lions ahead of next year's Super Rugby tournament.

'Lyon Rugby notes with horror that Franco Mostert is in Japan and is training with the Ricoh Black Rams while he has committed to 2 years with our club,' reads the club's official website statement.

'Faced with this serious violation of contract, law and basic values of rugby which are a commitment to be respected, the club will take all the necessary measures to see justice is done and today is approaching the competent legal and rugby authorities.'

After a superb Super Rugby campaign, Mostert made his Springbok debut in the mid-year Test series against Ireland. He did, however, agree to join Lyon before his involvement with the national squad.

Photo: Luigi Bennett/BackpagePix