German Chancellor Angela Merkel has discussed over phone with Afghan President Hamid Karzai the status of international forces in his country, including the length of time that German troops would stay in Afghanistan, a report of German magazine (Der Spiegel) said.The telephone conversation held late Wednesday, covered a "possible extension" in the length of time that German forces, currently numbering about 3,100, would remain, the report said, citing government sources in Berlin.The extension is a reference to a smaller number of German troops that could stay in Afghanistan after foreign combat troops end their mission in late 2014.Germany is planning to contribute up to 800 troops to an international effort to advise and train Afghan government forces after the withdrawal of combat troops.