Erdogan made the comments Tuesday at an Istanbul mosque, where hundreds held funeral prayers for Morsi, Egypt's first democratically elected president who was ousted by the military in 2013. Morsi died Monday after collapsing during a trial session.
Erdogan said: "Mohammed Morsi walked to join God during the trial. Whether this was a normal walk, or were there some other conditions involved, this is something to think about." He continued: "I don't believe that this was a normal death."
Erdogan also criticized authorities in Egypt for not allowing Morsi to be buried at his family's cemetery in his hometown. Earlier, the Turkish leader, who had forged close ties to Morsi, criticized Western nations for not speaking out against Egypt's current government.
The U.N. human rights office is calling for a "prompt, impartial, thorough and transparent investigation" into the death of former Egyptian president Mohammed Morsi, who collapsed and died inside a Cairo courtroom.
Rupert Colville, spokesman for the United Nations High Commissioner for Human Rights, noted concerns about the conditions of the former Muslim Brotherhood leader's detention since he was ousted by the military in 2013, including "prolonged solitary confinement."
Colville said the independent probe sought by the rights office should "examine whether the conditions of his detention had an impact on his death."
He noted that states — including Egypt — that have ratified the International Covenant on Civil and Political Rights have a "heightened duty" to protect the lives of detained people.
The rights office says the investigation should be conducted by a "judicial or other competent authority" that is independent of Egypt's government.
A main Syrian opposition group is mourning the death of Egypt's ousted former president, Mohammed Morsi.
The Turkey-based Syrian National Coalition said in a statement on Tuesday that while he was president, Morsi backed Syria's popular uprising against Syrian President Bashar Assad's government.
Morsi, who died in a Cairo courtroom on Monday, was a strong supporter of the Syrian opposition after he was elected president. Syrian activists circulated a video on Monday showing Morsi carrying a Syrian opposition flag during a rally in Egypt.
Assad's forces have largely quashed the popular revolt that erupted against the Assad family's decades-long rule in 2011, which was inspired by the Arab Spring protests that swept the region that year.
Mosques across Turkey have held funeral prayers for Egypt's ousted former President Mohammed Morsi, who had close ties to Turkish President Recep Tayyip Erdogan.
Morsi, Egypt's first democratically elected president ousted by the military in 2013, collapsed during a trial session in Cairo on Monday and died.
In the Turkish capital of Ankara, several hundred people held a protest outside the Egyptian Embassy on Tuesday, denouncing the government of current Egyptian President Abdel-Fattah el-Sissi and expressing support for Morsi's Muslim Brotherhood.
Erdogan, who described Morsi as a "martyr," was also to attend a symbolic funeral prayer in Istanbul, according to his office.
Egypt's authorities are criticizing a leading human rights advocate over her comments following the courtroom death the day before of Egypt's ousted former President Mohammed Morsi.
Morsi, Egypt's first democratically elected president ousted by the military in 2013, collapsed during a trial session on Monday and died.
Sarah Leah Whitson, Middle East director with the Human Rights Watch, criticized the Egyptian government's "failure to allow him adequate medical care, much less family visits."
Egypt's state information service says Whitson's statements were "nothing but false claims" and reaffirm what it called HRW's tradition of "circulating lies."
The service added that a court had approved Morsi's request in November 2017 asking that he be "treated at his own expense."
Iran is extending condolences to the Egyptian nation over the death of Egypt's ousted former president, Mohammed Morsi.
The Foreign Ministry's spokesman, Abbas Mousavi, says in a statement that, "while respecting the viewpoints of the great and brave Egyptian nation, the Islamic Republic of Iran offers its condolences to the Egyptian people, as well as Morsi's family and supporters."
Mousavi's statement added "wishes for divine blessing and mercy" for Morsi, who collapsed and died in a Cairo courtroom on Monday during a session in his trial on espionage charges.
Iran is an ally of Hamas, the Islamic militant group that rules the Gaza Strip. Hamas is also part of Morsi's Muslim Brotherhood movement but has taken measures in recent years to reconcile with the current Egyptian authorities.
Under Morsi, Iran's president at the time, Mahmoud Ahmadinejad, visited Cairo as ties between Egypt and Iran briefly improved, with Iranian tourists even visiting Egypt.
Human Rights Watch is calling on the U.N. human rights council to investigate the death of Egypt's ousted President Mohammed Morsi, who collapsed and died inside a Cairo courtroom the previous day.
The New York-based group also says that Egyptian authorities should be investigated for "their mistreatment" of Morsi, who collapsed during a court session and died on Monday "after years of insufficient access to medical care."
Sarah Leah Whitson, Middle East and North Africa director at HRW, says the authorities' treatment of Morsi in prison was "horrific, and those responsible should be investigated and appropriately prosecuted."
She says that "at the very least, the Egyptian government committed grave abuses against Morsi by denying him prisoners' rights that met minimum standards."
She added that Morsi death "followed years of government mistreatment, prolonged solitary confinement, inadequate medical care, and deprivation of family visits and access to lawyers."
A lawyer says Egypt's ousted President Mohammed Morsi has been buried, a day after collapsing and dying in a Cairo courtroom.
Abdul-Moneim Abdel-Maqsoud says Morsi's family attended funeral prayers early Tuesday in the mosque of Tora prison, then buried him in Cairo's eastern district of Nasr City.
He says there was heavy security at the cemetery.
The 67-year-old collapsed during a court session Monday.
Morsi hailed from Egypt's largest Islamist group, the now outlawed Muslim Brotherhood, and was elected president in 2012 in the country's first free elections following the ouster the year before of longtime leader Hosni Mubarak.
The military toppled Morsi in 2013 after massive protests and crushed the Brotherhood in a major crackdown, arresting Morsi and many others of the group's leaders.