Turkey international Hakan Calhanoglu will his forego his Bayer Leverkusen salary while he serves his four-month ban for breach of contract, the Bundesliga club announced on Tuesday.

The 22-year-old, Leverkusen's joint top-scorer with six league goals, is banned until May after the Court of Arbitration for Sport (CAS) last Thursday upheld a ruling by world football's governing body FIFA.

In January 2016, FIFA found Calhanoglu guilty of breach of contract.

In 2011, while still a teenager, the German-born forward signed a preliminary contract with Turkish side Trabzonspor, but then agreed to an extension with his then-club Karlsruher.

As well as the suspension Calhanoglu must pay Trabzonspor 100,000 euros ($108,000) in compensation, and he will be hit again in the pocket by a lack of earnings.

"Bayer had nothing to do with the incident at the time, but the club was hit hard by the punishment," said Calhanoglu in a statement from his club.

"This is why it is self-evident to me that I will not harm the club any further and will waive my salary for the duration of my suspension."

Leverkusen have said Calhanoglu will still train with the first team during his ban.

The club, whom he joined from Hamburg in 2014, say Calhanoglu is also looking into what options he has for a legal appeal.