Malawian President Bingu wa Mutharika died after suffering a cardiac arrest.

The 78-year- old president suffered a heart attack on Thursday and was admitted to hospital. Malawi plunged into a long night of intrigue after the reports of Mutharika's heart attack spread in the capital Lilongwe.

He was rushed to hospital, but doctors were unable to save him, a source at the hospital told, AFP.

"He died after two hours of resuscitation," the AFP has quoted a source as saying.

"The president died yesterday, and his body has been flown to South Africa for embalming and for the process to be dignified, the official announcement will come later on," a government official told AFP, speaking on condition of anonymity.

However, the death was not officially announced fearing constitutional crisis in the poor southern African country and the police deployed forces across the capital immediately after Mutharika was taken to hospital.

According to the Malawian constitution, Vice-President Joyce Banda would be taking over as the head of state. But Banda was ousted out of the party in 2010 after an argument about succession with the president.

"The laws of Malawi are very clear that the vice-president takes over when the president can no longer govern," former President Bakili Muluzi told journalists.

Mutharika was in favour of bringing in his brother Foreign Minister Peter Mutharika as the next president of the country and had even chosen him as the candidate of his ruling Democratic Progressive Party (DPP) for the presidential elections in 2014.

Mutharika became the president of Malawi in 2004. The former World Bank economist was re-elected to power with a sweeping majority in 2009.

But he was often criticised for his strict control over the media and for the attempts to keep the government policies away from public scrutiny.

The self-styled Economist in Chief was criticised for his authoritarian rule, economic mismanagement and nepotism and was facing mounting pressure to resign.