BERLIN (AP) — German Chancellor Angela Merkel's election challenger says he would suspend negotiations with the U.S. over a trans-Atlantic free trade agreement until Washington clarifies details about National Security Agency surveillance programs.

Social Democratic leader Peer Steinbrueck, who is running for chancellor Sept. 22, said Sunday on ARD public TV that "I would interrupt the negotiations until the Americans say if German government offices and European institutions are bugged or wiretapped."

He criticized Merkel's government for talking to Washington about a deal that would eliminate regulatory trade barriers between the EU and U.S., while at the same time "we don't know if the Americans may be sitting under our desks with some technical devices."

Germany's independent privacy watchdogs say the surveillance programs breach an EU-U.S. pact meant to ensure cross-border data protection.