Jean-Claude Juncker, the president of the European Commission, will be forced to testify in a case over the spying scandal that ended his 19-year rule as prime minister of Luxembourg.

Mr Juncker will only take the stand in November after he steps down as head of the EU’s civil service later this year, the head of Luxembourg’s prosecutor’s’ office said on Monday. 

A judge had earlier opened a criminal inquiry into whether officials tampered with a transcript of a secretly recorded conversation with Mr Juncker.

The “tampered” evidence is alleged to have misled an inquiry into illegal phone-tapping by disguising Mr Juncker’s role in the alleged wire-tap more than a decade ago. Mr Juncker has denied…