BERLIN, Oct 12 (Reuters) - Germany's parliament voted on Friday to renew the deployment of its troops in Afghanistan for another year, defying public opinion which is strongly against the mission. The Bundestag (lower house) agreed to extend the mandate for up to 3,500 German troops to participate in NATO's 40,000-strong International Security Assistance Force (ISAF) and for the deployment of six Tornado reconnaissance jets. The mandate is controversial in Germany, which has only gradually expanded its role in overseas military missions since World War Two. The deaths of more than 20 German soldiers in Afghanistan have further eroded public support. An OmniQuest poll for the Koelner Stadt-Anzeiger newspaper showed only 29 percent of Germans backed the extension. German troops are based mainly in Kabul and the north and the government has held out against NATO demands to help efforts to train Afghanistan's national army in the more dangerous south where NATO forces are fighting a fierce Taliban insurgency. Parliament will vote in November on extending the even more unpopular Operation Enduring Freedom mission which allows Germany to send up to 100 special forces to take part in anti-terrorism operations. (Reporting by Madeline Chambers, Editing by Richard Williams; Berlin Newsroom, +49 30 2888 5230, madeline.chambers@reuters.com)