Germany's federal commissioner for data protection, Ulrich Kelber, has reacted angrily to comments made by Ireland's data regulator, Helen Dixon, in which she defended Ireland's record on tech multinational investigations.
Mr Kelber, responding to a recent interview with Ms Dixon in the Irish Independent, accused her of "trying to turn a technical debate into a personal argument".
Ms Dixon told the Irish Independent Mr Kelber had "no experience in terms of the type of supervision that's being referenced", referring to Mr Kelber's repeated criticism of the Irish DPC's handling of Facebook.
She also took issue with comments made by Mr Kelber suggesting that Ireland lagged behind Germany or other EU countries in issuing fines to big multinationals.
Ms Dixon had been responding to incendiary remarks made by Mr Kelber in January, when he compared the behaviour of Ms Dixon's office to Germany's go-slow 'dieselgate' investigation.
German regulators have consistently criticised Ireland's regulatory approach to big US tech multinational firms, particularly Facebook.
They say Ireland's agency is under-resourced and that there is a structural reluctance to tackle US multinationals because of their employment bases here.
Ms Dixon's office has repeatedly denied the charges, arguing her 21 statutory investigations into big US multinational firms must be legally watertight to strengthen them against appeal when decisions are made.