ATHENS (Reuters) - Greek Prime Minister Alexis Tsipras defended plans to reform the country's pension system on Tuesday, saying it was a difficult but necessary plan to prevent the system from imploding. "Present and future projections leave no room for complacency," Tsipras said in a speech to parliament. "To pay pensions in 2016, the social security system - apart from contributions and state funding - will need to find additional funds of 980 million euros," he said. "We are choosing a difficult path, rather than this dead end." (Reporting By Renee Maltezou, writing by Michele Kambas)