Borussia Dortmund have announced the signing of 17-year-old Jude Bellingham from Birmingham City.The fee is rumoured to be £26 million, which makes Bellingham the most expensive 17-year-old in the world.The teenager travelled to Germany last week to complete a medical with the Bundesliga club, and the signing has now been made official.Per Sky Sports, Birmingham will be paid £25m up front and “several millions more” could be added depending on appearances, achievements and milestones.Dortmund beat out competition from some of Europe’s biggest clubs for Bellingham’s signature, including Chelsea, Real Madrid, Bayern Munich and Manchester United.United even offered the youngster a tour of their training ground with Sir Alex Ferguson in a bid to convince him to join.p1edlksoho1efpurdi101vjm131r9.jpgBut Dortmund won the battle and they announced the signing after posting a brilliant tease.On Monday morning, they posted a video on Twitter of Julian Brandt strumming the chords of The Beatles song “Hey Jude”.Brilliant.And then came the official announcement..."I can't thank Birmingham enough for what they have done for me, not just this past year but since the age of seven," Bellingham said after joining for Dortmund, per Sky Sports."Of course I wish everyone associated with the club nothing but the best. Once a blue always a blue."However, I'm incredibly excited to have joined one of Europe's biggest clubs. The direction they are heading in and how much they help to improve young players made it an easy decision for myself and my family."I can't wait to perform in front of all the fans when they are back inside one of the most beautiful stadiums in the world."

Per Sport Bild, Bellingham's contract will see him earn €3 million per year at Dortmund.