Poland striker Robert Lewandowski has said that he is committed to performing for Borussia Dortmund, despite having signed a contract that will see him move to league rivals Bayern Munich at the end of the season.

It was announced on Saturday that the prolific frontman will join Bayern on a five-year deal, but Lewandowski insists that he will still give his all for Dortmund until he leaves the club.

"We still have half a year ahead of us in which we have certain targets that we want to achieve together," the striker told the club's official website.

"Even if there are a few fans among you that don't agree with my decision, I hope for your support! In any case, I will give everything for Borussia Dortmund! Your Robert Lewandowski."

Dortmund are currently sitting in fourth position in the Bundesliga table.