Germany's parliament will hold a special session on reports the United States tapped Chancellor Angela Merkel's phone and left-wing parties demanded a public inquiry calling in witnesses including former U.S. intelligence operative Edward Snowden.
Her conservative party, now in talks with the opposition Social Democrats on forming a new governing coalition after the Sept. 22 election, said it would not stand in the way of any parliamentary committee investigating the espionage affair.
Reports last week that the U.S. National Security Agency had bugged Merkel's mobile phone stirred outrage in a country haunted by memories of eavesdropping by the Stasi secret police in old communist East Germany.
A rift over U.S. surveillance activities first emerged earlier this year with reports that Washington had wired European Union offices and monitored half a billion phone calls, emails and text messages in Germany in a typical month.
"These actions are intolerable, they have the power to destroy the ties of friendship that have always bound us to the U.S.," said Andrea Nahles, general secretary of the centre-left Social Democrats (SPD).
"A Bundestag (lower house of parliament) committee, which could shed light on the case, is unavoidable," Nahles told the Bild daily. "Edward Snowden could be a valuable witness."
A German newspaper said on Sunday that U.S. President Barack Obama knew his intelligence service was eavesdropping on Merkel as long ago as 2010, contradicting reports that he had told the German leader he did not know.
Merkel's Christian Democratic Union and the SPD have agreed to hold a special session of parliament on the spying scandal on Nov. 18, a spokesman for the conservatives said on Monday.
The SPD, Greens and radical Left party also are keen for parliament to set up an investigative committee.
The panel could call up witnesses in the scandal including the chancellor herself or Snowden, now living in asylum in Russia after he leaked details of U.S. spy programmes, the parties said.
Gregor Gysi, parliamentary leader of the Left, said Germany should include Snowden in its witness protection scheme so he could speak before the committee.