Egypt's first democratically elected president, Islamist leader Mohammed Morsi, was buried under heavy security early on Tuesday, a day after his dramatic collapse and death inside a Cairo courtroom, a member of his defense team said.

Morsi's son, Ahmed, said security agencies refused to allow Morsi to be buried at the family's cemetery in his hometown in Sharqia province, and instead had him interred at a Cairo cemetery dedicated to prominent Islamists.

Security agents turned reporters away from the cemetery, banning them from taking photographs of the funeral. Reporters were also barred from traveling to Morsi's hometown, according to Y.netnews.com.

The 67-year-old ex-president 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 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.

During his years in prison, Morsi, who was known to have diabetes, was often held in solitary confinement and was largely barred from receiving visitors. His family was only allowed to visit three times. While in detention, Morsi continued to appear in court on a range of charges.

In early court sessions he gave angry speeches until judges ordered him kept in a glass cage where they could turn off his audio.

His family attended funeral prayers in the mosque of Cairo's Tora prison, followed by the burial at a cemetery in the city's western district of Nasr City, said Abdul-Moneim Abdel-Maqsoud, a member of Morsi's defense team.

Morsi's Brotherhood on Monday accused the government of "assassinating" him through years of poor prison conditions. The group demanded an international investigation into Morsi's death and called on Egyptians to protest outside Egyptian embassies across the world.

Late Monday, Egypt's chief prosecutor said Morsi's body would be examined to determine the cause of his death. State TV, citing an unnamed medical source, said he died after suffering a heart attack.

Morsi collapsed Monday just after he had addressed the court, speaking from inside the glass cage and warning that he had "many secrets" he could reveal, a judicial official said.

In his final comments, he continued to insist he was Egypt's legitimate president, demanding a special tribunal, one of his defense lawyers, Kamel Madour told The Associated Press. State TV said Morsi died before he could be taken to hospital.