Borussia Dortmund's director of sport Michael Zorc told Kicker that some details have yet to be finalised and Kagawa is still contracted to the German league and cup winners until June 2013.
The club have already slapped a price tag of 20 million euros on their attacking midfielder with several Premier League clubs reported to be interested.
Earlier this month, Manchester United boss Sir Alex Ferguson flew to Berlin to watch Kagawa score in Dortmund's 5-2 win over Bayern Munich in the German Cup final.
Kagawa cost Dortmund just 350,000 euros when he joined from J-League side Cerezo Osaka in 2010. He has scored 21 goals in 49 Bundesliga appearances for Borussia, helping them win back-to-back league titles.