The Nigerian President Umaru Yar'Adua has died at his presidential villa following a long illness. Nigerian TV interrupted normal programmes to announce the news in a brief statement early today. The government has announced seven days of national mourning and said the president will be buried today in a Muslim ceremony later in his home state of Katsina, in the north of the country. Under the constitution, Vice-President Goodluck Jonathan, in charge since February, will be sworn in as the next leader. <br/>Mr Yar'Adua, 58, came to power in 2007 promising many reforms. Analysts say he made the most progress in tackling unrest in the oil-rich Niger Delta. <br/>The US President Barack Obama led tributes from world leaders. Mr Obama praised President Yar'Adua's profound personal decency and integrity, his deep commitment to public service, and his passionate belief in the vast potential and bright future of Nigeria's 150 million people. <br/>