Nigeria's acting President Goodluck Jonathan has been sworn in as head of state following the death of President Umaru Yar'Adua after a long illness. Mr Jonathan, in charge since February, will appoint a deputy and serve out the rest of the current presidential term until elections due next year. Mr Yar'Adua died late on Wednesday in the capital Abuja. TV broadcasts were interrupted with the news. Seven days of national mourning have been announced. Mr Jonathan took the oath of office in front of government ministers and other officials at the presidential villa in Abuja almost 12 hours after Mr Yar'Adua died. Mr Yar'Adua, who was 58, will be buried in a Muslim ceremony later on Thursday in his northern home state of Katsina, officials said. US President Barack Obama has led tributes from world leaders, praising Mr Yar'Adua's profound personal decency and integrity" and his "passionate belief in the vast potential and bright future of Nigeria's 150 million people". Mr Yar'Adua had been absent from the political scene since November, when he went to a hospital in Jeddah, Saudi Arabia, for several months. During that time he was not heard from, apart from a BBC interview. He returned to Nigeria in February but remained too sick to govern. Watch Goodluck Jonathan's swearing in ceremony Video credit: Youtube Source: BBC