Prince Rahim Al-Hussaini appointed new Aga Khan

Prince Rahim Al-Hussaini has been named the new Aga Khan, spiritual leader of millions of Shia Ismaili Muslims around the world.

He will take on the role from his father Prince Karim Aga Khan, who died on Tuesday at the age of 88.

The appointment was made after Prince Karim's will was unsealed, the Aga Khan Development Network said in a statement.

Prince Rahim Al-Hussaini Aga Khan V will be the 50th hereditary Imam of the Ismaili Muslims, who say they are direct descendants of the Prophet Muhammad.

The Ismailis are a Shia Muslim sect who revere a number of Imams, including Imam Ismail, who died in AD765.

They have a worldwide population of about 15 million, including 500,000 in Pakistan.

There are also large populations in India, Afghanistan and parts of Africa.

Prince Karim Aga Khan succeeded his grandfather as Imam of the Ismaili Muslims in 1957 at the age of 20.

He died surrounded by family in Lisbon, Portugal, which is the seat of the Isamili Imamat. A funeral will be held there in coming days.

During his time as the spiritual leader of the Ismaili Muslim community, the late Aga Khan helped found a charity responsible for running hundreds of hospitals, educational and cultural projects, mainly in the developing world.

He was also known for his immense wealth. Forbes magazine in 2008 estimated his fortune amounted to $1bn (£801m). Business ventures included hotels and telecommunications companies as well as a sizeable investments in horse breeding.

He was a leading owner and breeder of racehorses in the UK, France and Ireland, breeding Shergar, once the most famous and most valuable racehorse in the world.

The new Aga Khan is the eldest son of his late father and Begum Salimah, a British ex-model who converted to Islam and changed her name from Sarah Croker Poole.

The US-educated, Swiss-based Rahim is deeply involved with the network of charities and agencies his father helped spearhead.

According to the Aga Khan Development Network (AKDN) website, Prince Rahim has served on many of its boards and he currently chairs its Environment and Climate Committee.

"Prince Rahim has been particularly concerned with the AKDN's drive to protect the environment and mitigate the effects of climate change," the website said, adding that he was also interested in work "addressing the needs of those living in the greatest poverty".

Prince Rahim has two sons through his marriage to former American fashion model Kendra Spears.