The Bundesliga champions have offered to double the Japan international's wages, but the player is believed to have his heart set on a move to England or Spain in the summer
The 23-year-old has apparently been offered a contract extension by the German club until 2016 that would see his yearly wages double from €1.5 million (£1.25m) to €3m (£2.5m). However, he is believed to be ready to turn down the deal as he looks to force a transfer to England.
Kagawa has reportedly been given two weeks to decide on the offer. Should he decline, Dortmund will have no choice but to sell, or risk losing the player on a free transfer in the summer of 2013.
"There should be a decision soon. We would like to extend with him," Zorc told Bild.
However, he admitted: "The ball is in [Kagawa's] box - Shinji must now decide.
"We know that he is flirting with clubs in England and Spain."
In the past, Kagawa has claimed that joining Manchester United would be a dream and the attacker has thrived this season in the Bundesliga, scoring 12 goals and giving nine assists in 25 matches.
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