Germany’s top public prosecutor will look into accusations that the country’s BND foreign intelligence agency violated laws by helping the United States spy on officials and firms in Europe, including Airbus group, the federal prosecutors office said.

A spokesman for the prosecutors office confirmed weekend media reports that an investigation had been launched as opposition politicians demanded more information about the unfolding scandal from Chancellor Angela Merkel’s government.

“A preliminary investigation has been started,” the spokesman said. In a related development, federal prosecutor Harald Range himself will be questioned by a parliamentary committee looking into the affair in Berlin on Wednesday.

Der Spiegel said the BND helped the US National Security Agency over at least 10 years, embarrassing Germany and upsetting many in a country where surveillance is a sensitive topic due to abuses by the Nazis and the East German Stasi.

>>Read: Juncker on Germany’s BND scandal: ‘It is very difficult to keep secret services under control’

The magazine also reported that in 2013 the BND ordered staff to delete 12,000 internet “selectors” — IP addresses, email addresses and phone numbers of German government officials — that it had been tracking for the NSA.

Opposition members of parliament for the Greens and Left party have requested more information from Merkel’s government about the BND’s assistance to the NSA. German media said there were indications EU governments and agencies, especially France, were the targets of the BND’s spying for the NSA.

“This appears to be reaching a criminal dimension,” Christian Stroebele, a senior Greens member of parliament, told the Rheinische Post newspaper.

>>Read: German authorities sued over illegal spying allegations

Airbus Group AIR.PA said on Thursday it planned to complain to the German authorities over reports that the country’s foreign intelligence agency had helped the United States to spy on it and other European firms.

At the heart of the controversy is the scope of cooperation between the BND and NSA that began in 2002 after the September 11, 2001 attacks — and how long the Chancellor’s office was aware of BND’s activities on behalf of the NSA.

It is an especially touchy issue in Germany because Merkel and many Germans reacted strongly in 2013 to reports that the NSA had long been tapping Merkel’s cell phone. “Spying among friends is not at all acceptable,” she said at the time.