BERLIN (Reuters) - A senior member of Chancellor Angela Merkel's conservatives talked openly for the first time on Tuesday of the potential breakup of their coalition with the Social Democrats (SPD) due to a row over the activities of Germany's BND spy agency.
Critics accuse Merkel's staff of allowing the BND foreign intelligence agency to help the U.S. National Security Agency (NSA) spy on European firms and officials.
The row has dented Merkel's popularity and strained relations in her right-left coalition, with SPD leader Sigmar Gabriel - her vice-chancellor - challenging her over her role.
Michael Fuchs, the outspoken deputy parliamentary floor leader of Merkel's conservatives, raised the possibility of new elections in the Hannoversche Allgemeine Zeitung newspaper.
"What would happen if Angela Merkel went for early elections via a vote of confidence in parliament?" Fuchs said, pointing to polls showing his party might emerge with other coalition options.
While there is little sign that cautious Merkel would take such a drastic step, the remarks underscore the strains in the coalition, which is also at odds on policies ranging from EU-U.S. trade talks to aspects of its switch to renewable energy.
Fuchs said the Free Democrats (FDP), who shared power with Merkel from 2009-2013, are "at the door", ready to cross the 5 percent threshold needed to re-enter parliament. The pro-business party is trying to rebuild its support base after crashing out of parliament in the 2013 election.
Fuchs said the SPD should not "throw stones" at Merkel when its own support is weak. The SPD is hovering around 25 percent in most polls with Merkel's conservatives on around 42 percent.
Gabriel says the row could escalate if the suspicion persisted that the BND had helped the NSA spy on German firms. He wants parliament to see a list of targets, including Internet Protocol (IP) addresses of individual computers.
The content of the list is central to establishing whether the BND is at fault but the government says it must consult with Washington before releasing it.
Privacy is a potent issue in Germany due to extensive surveillance by Communist East Germany's Stasi secret police and also by the Gestapo in the Nazi era.
Horst Seehofer, head of the Bavarian sister party of Merkel's Christian Democrats (CDU), described Gabriel's behavior as "unacceptable in a coalition".
(Reporting by Madeline Chambers; Editing by Stephen Brown and Ralph Boulton)