Vice President Joe Biden and House Speaker Nancy Pelosi watch as German Chancellor Angela Merkel speaks before a joint session of the US Congress, November 3, 2009. (Tim Sloan/AFP/Getty Images)
"Zero tolerance needs to be shown when there is a risk of weapons of mass destruction falling, for example, into the hands of Iran and threatening our security," Merkel said in translated remarks to a joint meeting of the U.S. Congress.
"Iran needs to be aware of this, Iran knows our offer but Iran also knows where we draw a line," Merkel said.
Tehran and Washington have been at odds for years over Iran's nuclear program which Western powers fear is a covert effort to develop nuclear weapons. Iran has denies that and says it needs nuclear technology to generate electricity.
Western powers have urged Iran to accept a draft deal in which it would send most of its low-enriched uranium abroad by the end of the year for further enrichment to turn it into fuel for a medical reactor in Tehran.
However, on Monday an Iranian diplomat said additional talks were needed on the U.N.-drafted nuclear deal and that Tehran wants to import atomic fuel rather than send its own uranium abroad for processing.
"A nuclear bomb in the hands of an Iranian president who denies the Holocaust, threatens Israel and denies Israel the right to exist is not acceptable," Merkel said, referring to Iranian President Mahmoud Ahmadinejad.
