Borussia Dortmund announced on Sunday that they have signed Turkey international Omer Toprak for next season after activating the defender's release clause at Bundesliga rivals Bayer Leverkusen.

Toprak will sign a deal until June 2021 and the 27-year-old centre-back, who has made 25 appearances for Turkey, will reportedly cost Dortmund around 12 million euros ($12.9m).

He will bring a wealth of Champions League experience to Dortmund, who are third in the Bundesliga after Saturday's 1-0 over second-placed RB Leipzig.

"Toprak is a strong defender with international experience and great leadership qualities," Dortmund's sporting director Michael Zorc said.

Toprak has made 181 appearances in Germany's top flight, for both Leverkusen and ex-club Freiburg, scoring five goals.