An unexploded Second World War bomb has been discovered close to Borussia Dortmund's Signal Iduna Park ground.

The 550lb device, reported by German broadcaster DW as being of British origin,  was found on Thursday and plans are in place to try and defuse it.

The discovery came just hours before Dortmund boss Jurgen Klopp was due to give a news conference ahead of Saturday's derby against Schalke.

The 80,720-capacity stadium and the surrounding area was evacuated.

"It is not yet known how long the stadium area will remain off limits," Dortmund, who shut their Fan World space and club museum, said in a brief statement.

The bomb was found at a parking area to the west of the Signal Iduna Park and was discovered after viewing aerial photographs.

Finding unexploded World War II bombs is a relatively common occurrence in Germany where several million tonnes of bombs were dropped during the 1939-45 war by Allied and Soviet forces.

The city of Dortmund suffered extensive destruction during bombing raids.