Egypt's public prosecution has said it is probing the death of leading Muslim Brotherhood member Essam El-Erian.

El-Erian, who was serving various jail terms, died of a heart attack in prison on Thursday following a quarrel with another imprisoned Brotherhood member, according to informed sources.

In an official statement on Friday, the prosecution said it had received a notification from the prison authority on Thursday of El-Erian’s death.

The prosecution had taken procedures to investigate the incident by examining the body and assigning a forensic doctor to identify the cause of death, the statement added.

The forensic doctor's initial report confirmed that the body was free of any injuries of a criminal nature, the prosecution said.

Two other prisoners in cells adjacent to El-Erian's told the prosecution that his death was "natural without any criminal suspicion," assuring “the stability of his heath condition ahead of his death and the regularity of his receipt of treatment from the prison administration," according to the statement.

They also said they "did not notice anything that raised suspicion on the night of the prisoner's death, until they found out about [his death]," read the statement.

The officers in charge of the prison where El-Erian was held, as well as the prison's doctor and medical care director, told prosecutors that his death was natural and stressed he had received treatment and health care procedures regularly, according to the statement.

The prosecution said it would complete the investigation by attaching the Forensic Medical Authority's final report on the cause of death.