Germany on Friday rejected a request from the United States to send combat troops to southern Afghanistan, where most of the fighting with the Taliban and al-Qaeda is taking place, according to dpa. Defence Minister Franz Josef Jung said Germany would continue with its current mandate providing for the deployment of up to 3,500 troops, mostly in the relatively peaceful north of the country. Foreign Minister Frank-Walter Steinmeier and government spokesman Ulrich Wilhelm also ruled out a change in the German commitment, which was approved by parliament in October 2007. The officials were responding to a letter by US Secretary of Defence Robert Gates requesting German participation in a 3,200-man force to beef up the NATO presence in Afghanistan. The force is designed to replace 3,200 US Marines whose deployment was announced by Gates earlier this week for a period of seven months. Gates' letter asked Germany to consider a new mandate which could allow thousands more troops to be sent to Afghanistan, with some deployed to the more dangerous south. It also requests Germany provide helicopter support and paratroopers for the nearly 37,000-strong NATO-led International Security Assistance Force (ISAF). Germany currently has 3,200 troops in Afghanistan as well as six Tornado surveillance jets. Under the mandate German troops can only provide "emergency assistance" in the disputed south of the country. "The letter was not just sent to Germany but to all NATO allies as part of continued US efforts to increase troop numbers in Afghanistan," said a spokesman at the US NATO mission Brussels. "The letter asked all allies to dig deep and do as much as as they can to meet commanders' requests for more troops," he said. The spokesman said the US would repeat its call at an informal meeting of NATO defence ministers taking place in the Lithuanian capital of Vilnius from February 7-8. Germany's Sueddeutsche Zeitung daily said Gates warned of a split in the alliance if more troops were not sent to Afghanistan. The newspaper described the tone of the letter as "stern". Wilhelm said the letter, which was sent at the end of January, "came as a surprise." The Pentagon said earlier this week that it would urge NATO allies to send more troops to southern Afghanistan. The reluctance of European NATO allies to contribute extra soldiers or limit their role to peacekeeping missions has frustrated the United States, and most recently Canada. Canadian Prime Minister Stephen Harper announced Monday that he was extending the mission of his country's 2,500 troops in the country but criticized other NATO countries for refusing to send more soldiers. Harper said the extension was contingent on European allies sending more troops to meet requests for an additional 7,000 troops in the heavy fighting area of southern Afghanistan. There are already about 26,000 US soldiers in Afghanistan, about half of them under NATO's command. The German government has been considering a NATO request for combat troops for a Quick Reaction Force in northern Afghanistan to replace a 350-strong Norwegian force that leaves in July. Government sources said Germany would probably agree to the request.