The Aga Khan IV was laid to rest on Sunday at a private ceremony in Aswan, Egypt

The death of Prince Karim -- the 49th hereditary imam of the Shiite Ismaili Muslims -- was announced Tuesday by the Aga Khan Development Network and the Ismaili religious community. His son, 53-year-old Rahim Al-Hussaini, has been named as the Aga Khan V, the spiritual leader of the world's millions of Ismaili Muslims, according with his father's will.

On Saturday, a private funeral service took place at the Ismaili community center in Lisbon attended by Canadian Prime Minister Justin Trudeau, Spain's King Emeritus Juan Carlos and Portugal's President Marcelo Rebelo de Sousa.

The Aga Khan is considered by his followers to be a direct descendant of the Prophet Muhammad and is treated as a head of state.

The governor of Aswan welcomed Prince Karim's family at the southern Egyptian's provinces airport on Saturday.

"When his will was opened, it was found that he had requested to be buried in Aswan near his grandfather, Sultan Muhammad Shah, and his grandmother, Om Habiba," said Maj. Gen. Ismail Kamal.

Ismaili mourners marched as bells rang during the burial ceremony in the country's southern Aswan province, as Prince Karim's body was taken in a van. They carried his body, draped in a white shroud, and placed it on a yacht on the Nile River.

Prince Karim, 88, was given the title of "His Highness" by Queen Elizabeth in July 1957, two weeks after his grandfather, the Aga Khan III, unexpectedly made him heir to the family's 1,300-year dynasty as leader of the Ismaili Muslim sect.

The late Aga Khan evolved over decades into a business magnate and a philanthropist, moving between the spiritual and the worldly with ease. He was a defender of Islamic culture and values, but also widely regarded as a builder of bridges between Muslim societies and the West.

The Aga Khan Development Network deals mainly with issues of health care, housing, education and rural economic development. It says it works in over 30 countries and has an annual budget of about $1 billion for nonprofit development activities.

Ismailis lived for many generations in Iran, Syria and South Asia before also settling in east Africa, Central Asia and the Middle East, as well as Europe, North America and Australia more recently. They consider it a duty to donate up to 12.5% of their income to the Aga Khan as steward.