The retired army general, 77 -- whom the president accused of treason -- suffered cardiorespiratory arrest in the early morning hours and could not be resuscitated, an army statement said.

In May, police said they had set up a "medical care unit" at Humberto Ortega's home, a move interpreted by Nicaraguan media in exile as meaning he was under house arrest.

That came after he gave a media interview in which he said the president lacked a successor, and that his circle of power would collapse when he died.

A week later, the president accused his brother of having committed treason by decorating a US soldier in 1992.

In June, Nicaraguan press outlets operating in exile reported Humberto Ortega was transferred from his home to a military hospital with apparent heart trouble.

The Ortega brothers became estranged in the 1990s due to political differences.

They were both guerrillas in the Sandinista movement that initially took power in 1979 after toppling the US-backed Somoza family dictatorship.

After the movement's rise to power, Humberto Ortega headed up the army, while his brother headed the junta and later served as elected president from 1985 to 1990.

Daniel Ortega returned to power in 2007, and has since engaged in increasingly authoritarian practices, quashing presidential term limits and seizing control of all branches of the state.

Nicaragua has jailed hundreds of opponents, real and perceived, since then and shuttered more than 3,500 religious and other non-governmental organizations.

Most independent and opposition media now operate from abroad.