US Vice President Joe Biden on Friday warned Iran that opportunities for diplomacy over its disputed nuclear programme were not unlimited, as he kicked off a three-country European tour.
In an interview with the German Sueddeutsche Zeitung daily, Biden said the "burden of proof" that Iran was not seeking a nuclear weapon lay with the authorities in Tehran.
"President (Barack) Obama has made clear that containment is not an option. We will prevent Iran from getting a nuclear weapon," Biden was quoted as saying in remarks published in German.
"We think there is time and space for diplomacy -- accompanied with economic pressure. But this window will not be open for an unlimited time," he added.
He said Tehran could expect continued sanctions and increasing international pressure over its disputed nuclear drive, which Iran insists is entirely peaceful.
Biden is in Germany for a European trip that will also take in France and Britain.
He will meet Chancellor Angela Merkel later Friday before travelling to the southern city of Munich for the 49th edition of the Munich Security Conference, an annual gathering of defence officials and top brass.
He will deliver a speech on foreign policy there on Saturday and hold talks with Russian Foreign Minister Sergei Lavrov, UN-Arab League peace envoy Lakhdar Brahimi and Syrian opposition chief Moaz al-Khatib.
Biden will visit US troops in Germany on Sunday before heading to Paris on Monday for talks with French President Francois Hollande. The following day, he travels to London to meet Prime Minister David Cameron.