HAMBURG/BERLIN (Reuters) – Ex-Volkswagen VOWG_p.DE Chairman Ferdinand Piech, who resigned after a showdown with former chief executive Martin Winterkorn, has refused to testify to German lawmakers investigating a possible government’s role in the VW emissions scandal, according to his lawyer.

Piech, also VW’s former CEO who spearheaded the carmaker’s global expansion, gave testimony to lawyers of U.S. law firm Jones Day last April and to German prosecutors in Braunschweig near VW’s Wolfsburg headquarters in December, his lawyer said.

“These comments were solely directed at the inquirers of Jones Day and the prosecutors respectively. They were not directed at the public media,” Piech’s Hamburg-based lawyer, Gerhard Strate, said in an emailed statement.

He said Piech has no intention “to comment in public on what is being circulated as the alleged content of the questioning”.

The German parliamentary committee of inquiry has expressed its intention to summon Piech. The committee chairman did not return calls seeking comment on Piech’s refusal to testify.

A German media report earlier this week said Piech had informed top directors at VW about potential cheating with diesel emissions tests in the United States six months before the scandal became public in September 2015.

Piech has not commented on the report by Bild am Sonntag.

The unsourced report said Piech raised the issue with Winterkorn and subsequently informed members of the supervisory board’s steering committee in March 2015 – a month before Piech was ousted as chairman.

VW has said it might take legal action against Piech over his reported assertions. The supervisory board’s labor representatives have since denied the reported allegations, as did Stephan Weil, a member of the steering committee and prime minister of Lower Saxony state, VW’s No. 2 stakeholder.

The German parliamentary committee will next Thursday question Weil and Transport Minister Alexander Dobrindt over the scandal.

The panel was set up last April to clarify whether Germany’s federal government and regulators were involved in VW’s manipulations or failed to contribute towards their disclosure.

Last month it questioned Winterkorn, who denied early knowledge of the cheating.

(Reporting by Jan Schwartz and Andreas Cremer; editing by Mark Heinrich)