Ousted Egyptian President Mohamed Morsy, who was the country's first democratically elected leader, has died, according to Egyptian state media.

Morsy, 67, had been on trial for an espionage case when he suffered a heart attack, Egypt's state-run Al Ahram online reported.

"He was speaking before the judge for 20 minutes then became very animated and fainted. He was quickly rushed to the hospital where he later died," a judicial source said.

Morsi, a senior figure in the Muslim Brotherhood organization, was Egypt’s first democratically-elected president after the 2011 revolution, but he was deposed following a military coup led by Abdel Fattah el-Sisi in July 2013.

He had been serving a 20-year prison term on charges of ordering the arrest and torture of protesters, a 25-year jail term on charges of passing intelligence to Qatar and a three-year term for insulting the judiciary.

In November 2016, the Court of Cassation scrapped the life imprisonment sentence for Morsi and 21 other defendants, including some who had received the death penalty, in the same case and ordered a retrial.

Turkish President Recep Tayyip Erdogan became the first world leader to pay tribute to Morsi, calling him a "martyr."

"May Allah rest our brother Morsi, our martyr's soul in peace," said Erdogan, who had forged close ties with the late former president.