Berlin (AFP) - German intelligence services spied on top French officials and the European Commission on behalf of the American spy agency NSA, according to an article to appear Thursday in Sueddeutsche Zeitung.

Germany's BND foreign intelligence agency helped the National Security Agency (NSA) carry out "political espionage" by surveilling "top officials at the French Foreign Ministry, the Elysee Palace and European Commission" the German daily paper is to report.

Long portrayed as a victim of snooping by allies, Chancellor Angela Merkel's government has grappled this week with embarrassing reports of German spying on European firms on behalf of the United States.

Citing intelligence agency documents, the Bild daily reported Monday that the German chancellor's office was informed in 2008 during Merkel's first term of German involvement in US economic espionage but did not react.

According to Sueddeutsche Zeitung, spying on companies could only have taken place in isolated cases as the United States searched for "information on illegal exports."

"The heart (of the problem) is political espionage of European neighbours and institutions of the European Union," the paper claims, citing a source with knowledge of BND's procedures.

German Interior Minister Thomas de Maiziere, a trusted Merkel lieutenant who served as chief of staff at the Chancellor's Office from 2005-2009, has offered to provide an explanation next week to a parliamentary committee looking into NSA practices.

However, the opposition has already accused the government of lying for saying in writing April 14 that it knew nothing about any economic espionage by the NSA.

"I reject categorically the assertion that the government has not told the truth," Merkel spokesman Steffen Seibert said Wednesday at a regular press conference.

Germany reacted with outrage at revelations in 2013 by fugitive US intelligence leaker Edward Snowden that the NSA was conducting massive Internet and phone data sweeps, including in Germany.

The revelations, which included claims the NSA tapped Merkel's mobile phone, strained ties between Washington and Berlin.