Egypt's foreign minister on Thursday condemned as "irresponsible" accusations by Turkish President Recep Tayyip Erdogan that his ousted Egyptian counterpart Mohamed Morsi had been killed.

Read: Morsi was murdered, says Turkish president

In a statement, Sameh Shoukry strongly condemned the "repeated, irresponsible accusations by the Turkish president about Egypt," following Morsi's death on Monday after falling ill during a court hearing.

Erdogan was a close ally of Morsi during the Islamist's turbulent single year in office and since the military overthrew him in 2013, relations between Ankara and Cairo have deteriorated sharply.

On Wednesday, Erdogan accused Egyptian authorities of failing to take action to save Morsi's life after his collapse in a Cairo courtroom.

"Morsi was struggling on the floor in the courtroom for 20 minutes.

Authorities unfortunately did not intervene to save him," Erdogan said in a televised speech in Istanbul.

"Morsi was killed. He did not die of natural causes."

Since Morsi's overthrow, former army chief, now President Abdel Fattah al-Sisi has pressed ahead with a sweeping a crackdown on dissent that has seen thousands of Islamists jailed and hundreds facing death sentences.

Egypt has accused Turkey of giving refuge to fugitives from the crackdown.

There has been widespread criticism of the conditions of Morsi's detention during his nearly six years in custody, much of it in solitary confinement.

The UN human rights office has called for an "independent inquiry" into Morsi's death that would "encompass all aspects of the authorities' treatment ... to examine whether the conditions of his detention had an impact on his death."

A group of British parliamentarians in March 2018 warned Morsi's detention conditions, particularly inadequate treatment for his diabetes and liver disease, could trigger "premature death".