BLANTYRE, Malawi >> Malawi President Bingu wa Mutharika has died after a heart attack, doctors who treated him said today, as the troubled and impoverished southern African nation awaited official word of Mutharika’s death and who would succeed him.

The doctors, who spoke on condition of anonymity because they were not authorized to speak to reporters, said the 78-year-old died Thursday, and his body was then flown to South Africa, apparently to buy time for politicians who may be squabbling over the succession.

Malawi’s government has so far issued only a brief statement on state radio and television, saying Mutharika was taken ill and was flown to South Africa for further treatment.

A Cabinet minister, speaking on condition of anonymity because the matter is sensitive, said announcing the death required taking political steps. He did not elaborate, but questions over succession are likely complicating matters.

Under the constitution, Vice President Joyce Banda, 62, should take over to complete Mutharika’s term, due to end in early 2014. But Banda has clashed with Mutharika. She was expelled from his party and formed her own. She remained vice president.

Mutharika’s brother, Foreign Affairs Minister Peter Arthur Mutharika, may try to challenge Banda for leadership, though the constitution appears clear that the vice president should take over.

At a news conference in Lilongwe, the capital, today, Banda indicated she was being frozen out, saying she had turned to South African officials for information on Mutharika.

“The people of Malawi have the right to know the state of health of President Bingu wa Mutharika,” she said. “I am appealing to the people of Malawi that we must abide (by) the rules. The laws say if the president is incapacitated the vice president takes over. It’s my hope that Malawians shall adhere to the constitution.”

Undule Mwakasungula, a Malawian civil rights activist, said he was confident Banda would become president, as the constitution dictates. He said he had heard key figures, including the chief justice and army commander, had given her their support.

The vice president’s succession is “part of the constitutional order,” he said. “I think there are developments taking place right now. I think there are processes. I think there are discussions. There will be an announcement quite soon.”

Voice Mhone, another activist, also said he expected Banda to take over. But he said even a brief period of uncertainty was worrying, given the nation’s economic troubles.

“The economy might even go down further because of a lack of short-term leadership,” he said, adding that many Malawians were too concerned with the daily struggle to survive to pay much attention to politics.

Mutharika’s predecessor and former mentor Bakili Muluzi decried the official silence on Mutharika’s death and on the nation’s political future.

“The present scenario where the government’s machinery is almost silent on the health status of our president is very unfortunate and ought not to continue,” Muluzi said at a press conference at his home in Blantyre, Malawi’s commercial hub. “It is the constitutional duty and indeed good practice of the government to inform its citizens and the world community timely, accurate and transparent information about the particulars of the ongoing treatment and health condition of their state president.”

When Mutharika first came to power, he was backed by Muluzi.

A feud ensued after Mutharika had Muluzi charged with corruption and fraud. Mutharika left the ruling party to establish his own. Political bickering between the two men led to extensive legislative delays, rioting, a failed impeachment bid, and accusations of coup and assassination plots.

Mutharika’s death could set off turmoil worse than the aftermath of his falling out with Muluzi. At her news conference, Banda called for calm.

Mutharika was a former World Bank official once heralded for his stewardship of one of the world’s poorest countries. In recent years, he has been accused of trampling on democratic rights.

Mutharika first came to power in a 2004 election, and was overwhelmingly re-elected five years later.

During his first term, Mutharika persisted with a program to help farmers buy fertilizer even though Western donor nations and agencies said subsidies should be avoided in a free market. His subsidies were credited with boosting Malawi’s economy.

In more recent years, the economy has stumbled, with shortages of fuel and foreign currency and high unemployment.

Anti-government demonstrations across Malawi last year were met with an unprecedented security crackdown that resulted in at least 19 deaths.

Malawi’s relations with foreign donors have been strained by accusations Mutharika is authoritarian and responsible for human rights abuses. Last month, a U.S. aid agency that rewards good governance suspended $350 million worth of assistance to Malawi.