President Francois Hollande says French troops are taking part in operations against Islamists in northern Mali. French troops "have brought support this afternoon to Malian units to fight against terrorist elements", he said. Armed groups, some linked to al-Qaeda, took control of northern Mali in April. Mr Hollande said the intervention complied with international law, and had been agreed with Malian President Dioncounda Traore. A state of emergency has been declared across the country. Mr Traore used a televised address on Friday to call on Malians to unite to "free every inch" of the country. He said he was to launch a "powerful and massive riposte against our enemies" after he "called for and obtained France's air support within the framework of the international legality". The militants said on Thursday that they had advanced further into government-controlled territory, taking the strategic central town of Konna. http://www.bbc.co.uk/news/world-africa-20991719