By Manchester correspondent

Manchester United want Ilkay Gundogan to sign a pre-contract ahead of his expected summer move, Football Insider sources understand.

United have agreed a deal in principle with Borussia Dortmund for the 24-year-old midfielder to join the Premier League club this summer for a fee of £21.5million.

Now United want Gundogan to demonstrate his commitment to the deal by tying him down to a formal contract.

Dortmund announced earlier this week that Gundogan will not extend his agreement with the Bundesliga club beyond 2016, paving the way for a summer transfer.

United made a formal move for the midfield anchorman after identifying him as the long-term successor to Michael Carrick.

The England international recently signed a 12-month contract extension and will continue to be part of Louis van Gaal’s plans next season but the manager has sanctioned a swoop for Gundogan after being convinced he has fully recovered from the back problem that sidelined him for 14 months.

United have extensively scouted the Germany international for the last three years after he was a central figure in Dortmund’s 2011-12 Bundesliga triumph.

Gundogan is set to be the first of a number of high profile signings by United this summer as they prepare to spend up to £200million on new players.

Gundogan, who joined Dortmund from Nuremberg in the summer of 2011, has decided to follow Jurgen Klopp out of the club.

Klopp announced earlier this month that he will leave Dortmund at the end of the season, with Mainz manager Thomas Tuchel appointed as his successor.