The Egyptian government accused the United Nations high commissioner for human rights of politicizing the death of Egypt's former president Mohamed Morsi after the UN office asked for an investigation to be carried out by a non-partisan body.

The Egyptian foreign ministry's spokesperson Ahmed Hafez criticized the statement of Rupert Colville, the UN office spokesperson, accusing him of deliberately politicizing the natural death of the deposed Islamist leader.

"The statements included insinuations to doubt and slander the state institutions and the integrity of the Egyptian judicial system," Hafez said in a statement.

"It is an ill-intentioned attempt not only undermining Egypt's commitment to international standards but also jumping to unsubstantiated conclusions without any proof of what was mentioned," he added.

The Egyptian spokesperson considered Colville's words "unacceptable, especially with the suggestion of specific measures to be taken by Egypt that are already applied by the Egyptian authorities."

Colville said Tuesday that the Egyptian authorities should make sure that Morsi, who collapsed and died during a court hearing on Monday, had received proper medical care.

"As former president Mohammed Morsi was in the custody of the Egyptian authorities at the time of his death, the state is responsible for ensuring he was treated humanely and that his right to life and health were respected," Colville highlighted.

"The investigation should therefore also encompass all aspects of the authorities' treatment of Mr. Morsi to examine whether the conditions of his detention had an impact on his death," the UN office spokesperson said.

Hafez concluded that Colville's statement will be discussed at the highest level as it lacked objectivity and professionalism.

Morsi, the only democratically elected president in Egyptian history, died after spending six years in detention under harsh conditions that included near-complete solitary confinement and the denial of proper medical care.

Already serving a life sentence for previous convictions, the 67-year-old passed out in court during a session of his trial for espionage and was pronounced dead on arrival at a Cairo hospital.

He was buried Tuesday morning in a cemetery dedicated for leaders of the Muslim Brotherhood in eastern Cairo's Nasr City district after the Egyptian authorities had refused to allow the ex-president to be buried at his family's grave in his hometown in al-Sharqiya governorate.

Morsi had been one of the now-outlawed Muslim Brotherhood leaders and became Egypt's president in 2012 before being ousted by the man he appointed as defense minister, then-General, now-President Abdel Fattah al-Sisi, in 2013.

The prosecutor's office announced Monday an investigation had been launched to determine the causes of Morsi's death because the reasons had not been yet indicated.

Morsi was a contentious figure in Egyptian politics whose rise to power exemplified a brief moment of political freedom following the 2011 revolution that ended the three-decade dictatorship of his predecessor, ex-president Hosni Mubarak.

However, Morsi's hold on power was weakened by general discontent. EFE