Germany's parliament has voted to extend the mandate of troops serving in Afghanistan for one year but did not lift the upper limit of soldiers able to be sent there, currently set at 4,500.The Bundestag lower house voted 445 deputies out of 594 in favour of the motion, which will ensure that German troops stay in the country until at least December 2010.Germany currently has about 4,300 troops in Afghanistan, the third-largest contributor to a 110,000-strong international force after the United States and Britain. Anders Fogh Rasmussen, Nato's secretary general, said on Wednesday that members of the military alliance would send at least 5,000 troops to back the US increase of 30,000 extra soldiers announced by Barack Obama, the US president, on Tuesday.But the full extent of extra resources coming from the military alliance remains unclear.