Malawi President, Bingu wa Mutharika has died after a heart attack, medical and government sources indicated today.The 78-year-old had been rushed to a Lilongwe hospital on Thursday after collapsing but was dead on arrival, sources said.The constitution makes clear that Vice-President Joyce Banda is first in line to take over as head of state, although Banda’s expulsion from the ruling party in 2010 may complicate the transition.Mutharika, a former World Bank economist who had been accused of despotism and mishandling the economy in his final months, appeared to have been grooming his Foreign Minister brother Peter as his successor.Peter Mutharika had tended to deputise in his brother’s absence.Police deployed in force across the capital on Thursday after Mutharika's admission to hospital, while 15 army officers took up position around Banda’s residence, witnesses said.Two weeks ago he vowed to govern until his term ends in 2014 after a leading rights group threatened unrest if he did not resign or call a referendum on his leadership."I would like to say that Bingu doesn’t run away from work, Bingu doesn’t desert responsibility even if the going gets tough,” he told a rally.Last month, the Public Affairs Committee (PAC), made up of religious groups, rights activists and the opposition, demanded that Mutharika quit office or call the referendum within three months.The group accused him of mismanaging the economy and trampling on democratic freedoms, saying the country was bordering on a failed state.Critics have lambasted new laws to restrain the media, limit protests, and restrict lawsuits against the government.Political tensions erupted into rioting in July, when police shot 19 people dead.Ahead of the riots, alarmed by his restrictions on political freedoms, donors had already begun suspending aid, with former colonial power Britain slashing its financial support.