BERLIN — Chancellor Angela Merkel's chief of staff testified Thursday to a parliamentary committee about alleged surveillance by the U.S. National Security Agency, but failed to satisfy opposition lawmakers who are attacking the government on the issue ahead of Germany's September elections.

Merkel's center-left opponents have asserted that she hasn't been doing enough to confront Washington and protect Germans' personal data. They also are questioning official claims of ignorance about U.S. programs and are demanding answers on what Germany's own intelligence services may have known about them. Merkel's chief of staff, Ronald Pofalla, is responsible for coordinating German intelligence agencies.

"All questions that related to the work of the German intelligence services have been cleared up so that I can state today: The German intelligence services work in accordance with the law," Pofalla said after testifying to the Parliamentary Control Body — a closed-doors, cross-party committee that supervises German intelligence.

"The suspicion has been aired that German citizens' data were transferred en masse to the U.S., to the NSA," he said. "This assertion is clearly wrong."

However, panel chairman Thomas Oppermann — a prominent lawmaker with the opposition Social Democrats — said the meeting made no real progress.

"We still don't know anything about the extent and the concrete practice" of the widespread surveillance alleged by NSA leaker Edward Snowden, he said.

Protecting personal data is generally a more sensitive issue in Europe than in the U.S. — and particularly in Germany, not least because of memories of surveillance and repression by communist East Germany's secret police, the Stasi and the Nazis' Gestapo.

Merkel is seeking a third term in Sept. 22 parliamentary elections and her party leads polls. Surveys so far indicate that, while many Germans are skeptical of her insistence that she wasn't aware of U.S. surveillance programs, the issue hasn't yet affected their voting intentions.