The German government on Monday rejected suggestions that it intentionally misled the public about the United States' willingness to negotiate a "no-spy" agreement between the two countries.

Chancellor Angela Merkel's then-chief of staff, Ronald Pofalla, said a few weeks before German elections in 2013 that the two countries would start talks on an agreement not to spy on each other. The statement came after revelations by Edward Snowden about National Security Agency surveillance.

However, a report Saturday by the Sueddeutsche Zeitung newspaper and two broadcasters, based on email correspondence between the governments, suggested there was no firm indication at the time that the White House would conclude such a deal.

Pofalla was untruthful "for the purposes of electoral tactics," Torsten Schaefer-Guembel, a deputy leader of the center-left Social Democrats, the junior party in Merkel's governing coalition, told the daily Tagesspiegel.

Merkel on Monday reiterated her willingness to testify before a parliamentary panel that is looking into the NSA's activities.

"I can only say that everyone worked according to their best knowledge and conscience — that goes for today's chief of staff but also his predecessor," Merkel told reporters.

The government has faced questions in recent weeks over allegations that Germany's own spy agency may have helped the U.S. spy on European companies and officials as long ago as 2008.

The agency is overseen by Merkel's chief of staff, and the Social Democrats — who are struggling in opinion polls — have appeared keen to put her office under pressure. However, there has been no sign yet of questions over NSA surveillance damaging her party's popularity.

"For me, it is a matter of course that intelligence agencies must keep to German laws when they are active in Germany," Merkel said.

"Enforcing that may perhaps be difficult, may take longer than we want, but it remains a political aim for me."