German Chancellor Angela Merkel defended her present and past chiefs of staff on Monday against criticism that they lied to the public about the prospects of a "no-spy agreement" with the United States.

Media reports alleging lying by Merkel's aides were the latest in a controversy over German intelligence since former NSA contractor Edward Snowden revealed in 2013 a wide-spread U.S. surveillance programme that included tapping her cellphone.

The latest report said Washington never offered Germany a no-spy agreement after those revelations, despite statements from Merkel and senior aides during the campaign for Germany's general election held only a few months later.

Vice Chancellor Sigmar Gabriel, head of Merkel's Social Democratic (SPD) junior coalition partners, last week publicly asked Merkel's role in the affair, which put strains on SPD's grand coalition with Merkel's Christian Democrats.

"I can say here publicly that everybody worked to the best of their knowledge," Merkel said on Monday, adding that this included her chief of staff Peter Altmaier as well as his predecessors Ronald Pofalla and Thomas de Maiziere.

Snowden's revelations about wide-ranging espionage by the U.S. National Security Agency (NSA) caused outrage in Germany when they first surfaced in June 2013.

Recent reports said Germany's BND foreign intelligence agency helped the NSA spy on European targets with the blessing of Merkel's aides.

Merkel said her office, which oversees the intelligence services, would hand over all documents needed by parliament. However, the chancellery has so far rejected SPD demands to make public a list of IP addresses, search terms and names the BND had been tracking for the NSA.

These are widely seen as being crucial to establishing whether the BND was at fault in helping the NSA.

Merkel has defended cooperating with U.S. agencies to fight international terrorism and says she would answer questions by a parliamentary committee.

Raising the pressure on Merkel, SPD Secretary General Yasmin Fahimi said on Monday: "If it's true the U.S. never held out the prospect of such a no-spy agreement between Germany and America, then the conservatives lied in the 2013 election campaign."

Former Justice Minister Sabine Leutheusser-Schnarrenberger from the Free Democrats (FDP), who were in coalition with Merkel's conservatives from 2009-2013, joined the attack, telling Der Spiegel magazine's online edition: "In the end, the chancellery pulled the wool over people's eyes."

The issue of BND cooperation with the NSA is sensitive in Germany, where privacy is highly valued after the extensive snooping by the Stasi secret police in Communist East Germany and by the Gestapo in the Nazi era.