BERLIN, March 13 (Reuters) - German Chancellor Angela Merkel is looking forward to an elaborate exchange of views on a variety of issues with U.S. President Donald Trump when they meet in Washington on Tuesday, Merkel's spokesman Steffen Seibert said on Monday. Seibert said that the two leaders will meet for more than 2-1/2 hours and will then continue their deliberations at a working lunch after that. "The chancellor is looking forward to the opportunity to have a detailed exchange of views with the American president," Seibert told a news conference in Berlin. "Germany and the United States of America are partners. The list of our common interests is a very long one." Seibert said the German government believes protectionism is not conducive to global economic growth. "We continue to believe that free trade has advantages for everyone involved. We don't believe in world economic order based on protectionism."