Mohammed Morsi
Mohammed MorsiReuters

The UN human rights office on Tuesday called for an "independent inquiry" into former Egyptian president Mohammed Morsi's death while in state custody.

"Any sudden death in custody must be followed by a prompt, impartial, thorough and transparent investigation carried out by an independent body to clarify the cause of death," said Rupert Colville, spokesman for the UN High Commissioner for Human Rights, according to the AFP news agency.

"Concerns have been raised regarding the conditions of Mr. Morsi's detention, including access to adequate medical care, as well as sufficient access to his lawyers and family, during his nearly six years in custody," added Colville.

He noted that Morsi "also appears to have been held in prolonged solitary confinement," and said the investigation must "encompass all aspects of the authorities' treatment of Mr. Morsi to examine whether the conditions of his detention had an impact on his death."

Morsi, the first democratically elected head of state in Egypt’s modern history, died at the age of 67 after collapsing in a Cairo court while on trial on espionage charges.

He was ousted by the army in 2013 amid mass protests against his rule.

The Muslim Brotherhood, of which Morsi was a member, said his death was a “full-fledged murder” and called on Egyptians to gather for a mass funeral.

Morsi had already been sentenced to a total of 45 years in prison in various trials. In December of 2017, he was sentenced to three years in prison for "insulting the judiciary".

In September of that year, a court in Egypt upheld a life sentence against Morsi on charges stemming from a trial over spying for Qatar.

In 2012, he was sentenced to 20 years in prison after being convicted of inciting the killing of protesters, in an incident that saw 10 people gunned down outside the presidential palace in December 2012.