Chelsea have signed Borussia Dortmund forward Christian Pulisic for 64m euros (£58m), but will loan him back to the German club until the end of the 2018/2019 season.

This is the highest transfer fee for an American player. Dortmund director Michael Zorc said: “It was always Christian’s dream to play in the Premier League.

“That certainly has to do with his American background, and as a result we were unable to extend his contract. Against this background, we have decided to accept an extremely lucrative bid by Chelsea, given the low contract maturity.”

Pulisic in an emotional tweet said he will leave Dortmund with a “heavy heart”.

“It feels like only yesterday that I arrived in Dortmund as a raw, excited, very nervous but exceptionally proud 16-year-old from a small American town called Hershey,” he said.

“I would not be here without the club and their belief in giving young players a chance. Many memorable moments stand out – to have experienced all of them before my 20th birthday, still feels at times like a dream.

“For the next six months, it’s all BVB. Please do not doubt my passion, determination and my 110% commitment to the team right until the last ball is kicked this season.”