Supporters join Turkish President Recep Tayyip Erdogan, who attended funeral prayers in absentia for ousted former Egyptian President Mohammed Morsi, at Fatih Mosque in Istanbul. Picture: Emrah Gurel/AP

Cairo - Egypt on Thursday said that Turkish President Recep Tayyip Erdogan's claim that former Islamist president Mohammed Morsi was killed is a "baseless" allegation.

Morsi, who was deposed by the military in 2013, died on Monday after suddenly collapsing inside a courtroom in Cairo.

Egyptian state media said that Morsi, a senior official in the now-outlawed Muslim Brotherhood, died of a heart attack.

On Wednesday, Erdogan said Morsi did not die of natural causes, but was killed. He vowed that Turkey "will do whatever is needed to put Egypt on trial in international courts."

In response, Egyptian Foreign Minister Sameh Shoukry on Thursday said that his country was ready to face any threats.

"Such unproven talk, with which he [Erdogan] fills his speeches and statements, only reflect the fact of his close link to the terrorist Brotherhood organization," Shoukry said in a written statement.

Turkey's President Recep Tayyip Erdogan has claimed that former Egyptian President Mohammed Morsi did not die of natural causes but that he was killed. Picture: Presidential Press Service via AP

The Egyptian official called Erdogan's remarks "irresponsible."

Ties have strained between Egypt and Turkey since the army's mid-2013 overthrow of Morsi following mass protests against his rule.

Morsi, who died aged 67, was Egypt's first democratically but divisive president. After his ouster, he was detained and tried in several cases.