PARIS, Dec 6 (Reuters) - German Chancellor Angela Markel said on Thursday Iran remained a threat. "Iran continues to represent a threat," Merkel said at a joint news conference with French President Nicolas Sarkozy in Paris. The U.S. National Intelligence Estimate, released on Monday, appeared to contradict past assertions by the administration of U.S. President George W. Bush that Iran is intent on building a bomb. (Reporting by Francois Murphy; writing by Kerstin Gehmlich; Editing by Jon Boyle)