LILONGWE: Malawian police arrested four former cabinet ministers on Monday on suspicion of plotting to overthrow the government after the death of President Bingu wa Mutharika in April last year, police said.

The four, who included the late Mutharika's younger brother, Peter, were found by an official inquiry to have tried to prevent then vice-president Joyce Banda from taking power, as stipulated in the constitution.

“In total, four former ministers have been arrested for questioning in connection with the investigations into the death of the President as revealed in the inquiry report,” police spokeswoman Rhoda Majolo said.

Banda took charge of the impoverished southern African nation after the unexpected death of Mutharika, who spent his last years in office cracking down on opponents and battling with diplomats.

The United States and other key western donors suspended aid in 2011 after police shot and killed at least 20 protesters demonstrating against Mutharika's rule.

Banda, who had also fallen out of favour with Mutharika by the time of his death, set up an inquiry into the circumstances surrounding the incident after conflicting reports about when he died.

Its findings, revealed last week, showed Mutharika died of a heart attack on his way to hospital in Lilongwe on April 5, and not on April 7 in South Africa, as originally claimed by the government and Mutharika's family.

The report also revealed that Peter Mutharika, who was then foreign minister, and former finance minister Goodall Gondwe attempted to convince the army to take over and stop Banda from ascending to power.