Malawi's President Bingu wa Mutharika, 78, was unconscious in hospital Thursday after suffering a heart attack, a medical source said.

"He had a cardiac arrest, he is still unconscious since 9:00 am (0700 GMT)," a senior official at Kamuzu Central Hospital in Lilongwe said on condition of anonymity.

Mutharika, a former World Bank economist, was re-elected in 2009 as president of the poor southern African country.

His second term has been marred by anti-government protests, with activists accusing him of mismanaging the economy and trampling on democratic freedoms.

Two weeks ago he vowed to govern until his term ends in 2014, following demands for his resignation and growing anger over his leadership.