BERLIN (AP) — The German government acknowledged “shortcomings” at the country’s foreign intelligence agency Thursday, following allegations that it may have helped the United States spy on Europeans.

German weekly Der Spiegel reported on its website Thursday that the Federal Intelligence Agency for years monitored telecoms traffic using filters provided by the U.S. National Security Agency. The magazine reports that by 2008 German intelligence agents had discovered that some of the filters — known as selectors — related to European arms companies and French authorities. But spy chiefs reportedly failed to inform the government for several more years until the agency, known by its acronym BND, came under parliamentary investigation over its links to the NSA in the wake of Edward Snowden’s revelations.

Government spokesman Steffen Seibert said in a statement that the agency, which answers directly to Chancellor Angela Merkel’s office, had been asked to “thoroughly clarify this complex matter.”

“Technical and organizational shortcomings have been identified at the BND,” he added, but said the government had no evidence of “massive eavesdropping against German or European citizens.”

Opposition lawmakers called for the head of the agency, Gerhard Schindler, to resign.

“It’s obvious that the BND for years lied to Parliament and to the government about the extent and purpose of its cooperation with the NSA,” said Martina Renner, a Left Party lawmaker who sits on the parliamentary intelligence oversight committee.

The telecoms monitoring was part of a closer cooperation between the BND and its American counterparts in the wake of the 9/11 terror attacks. Several of the attackers spent time in the north German city of Hamburg.