Abdullah Morsi, the son of late Egyptian President Mohammed Morsi, died late Wednesday due to a sudden heart attack, the Anadolu Agency reported, citing a family source.

It is still unknown what may have caused the stroke.

His father also reportedly died from a heart attack during a court session. The country's state television reported early Tuesday that Morsi was "suffering from a benign tumor, had continuous medical attention and his death was caused by a heart attack."

He was buried in Nasr City, east of Cairo.

Morsi was elected president in 2012 but was ousted in a military coup a year later. The military crushed the Muslim Brotherhood movement in a major crackdown, arresting Morsi and many others of the group's leaders, who have been in prison undergoing multiple trials ever since the coup.

Turkey's relations with Cairo deteriorated after the Egyptian military, then led by el-Sissi, ousted Morsi. Erdoğan has strongly condemned Morsi's ouster.

Amnesty International and other rights groups have called for a fair, transparent and comprehensive investigation into Morsi's death and raised questions about his treatment in prison. Egypt's government has dismissed accusations that he was badly treated.