Borussia Dortmund’s Japan star Shinji Kagawa is planning a switch to either Premier League giants Manchester United or Chelsea, according to a report in German daily Bild.

The 23-year-old has been in stellar form this season and his 12 goals in 25 league games have helped defending champions Dortmund stay on top of the German league with six games remaining.

But according to Bild, Kagawa is considering rejecting Dortmund’s offer to double his wages from 1.5 million to three million euros ($A1.93 million to $A3.86 million) per season and extend his contract, which is due to expire in June 2013, until 2016.

Both Manchester United and Chelsea are reported to be interested in signing the Japan star and reports in the German media claim Kagawa is worth about 15 million euros ($A19.31 million).

“There will be a decision made soon,” said Dortmund manager Michael Zorc.

“We would love to extend to his contcngland or Spain.”

Kagawa has been one of the German league’s star finds, having signed from Cerezo Osaka in 2010 for 350,000 euros.

He scored two goals leading Dortmund’s attack in their recent 6-1 thrashing of Cologne.