Bill Gates' philanthropic body, the Bill and Melinda Gates Foundation, has been accused of complicity in the torture of Palestinian prisoners through its investment in British security company G4S.
G4S provides security services and equipment at Israeli prisons where allegations of child torture, forced confessions, overcrowding and medical neglect have been raised.
The foundation, the largest in the world, last year purchased £110m ($172m) worth of shares in G4S, something that human rights charities, such as Addameer Prisoner Support, claim contradicted the foundation's belief that "every life has equal value".
A petition from the Addameer charity claims that "the Gates Foundation is legitimising and profiting from Israel's use of torture, mass incarceration and arbitrary arrest to discourage Palestinians from opposing Israel's apartheid policies".
The calls come as people around the world participate in protests against Israeli prisons and G4S' role on Palestine Prisoner's Day (17 April).
More than 5,000 Palestinians, including 183 children, are currently in detention in Israeli prisons.
War on Want's senior campaigns officer Rafeef Ziadah said: "Through its shameful holdings in G4S, the Bill and Melinda Gates Foundation, the biggest charitable foundation anywhere, is legitimising and profiting from the multinational's complicity in Israel's military occupation and imprisonment of Palestinians.
"Along with many human rights organisations across the world, we urge the foundation to divest from G4S now."
Investment arm separate
The foundation told IBTimes UK that the Asset Trust, which manages the foundations investments, was a "separate entity from the Bill & Melinda Gates Foundation and its investment strategies are set by its trustees".
"We understand the passion of people standing up for injustice. That is what motivates us all at the foundation every day," said a statement from the foundation.
"The Asset Trust is the body that makes the investments to which people are referring and it is actively managed so the foundation has the most money possible to support the great work the foundation does with partners around the world."
G4S also maintains security equipment at Israeli checkpoints along the wall which separates Israel from the Occupied Palestinian Territories of Gaza and the West Bank.
Ramah Kudaimi, a coordinator at the American coalition US Campaign to End the Israeli Occupation, told One World: "The Gates Foundation should be ashamed of profiting from a company complicit in Israel's grave mistreatment of Palestinian prisoners.
"Bill and Melinda cannot claim to be trying to help every person get the chance to live a healthy, productive life while investing in torture and mass incarceration."
Under Article 76 of the UN Fourth Geneva Convention, governments - such as Israel's - are forbidden from transferring prisoners from occupied territory to the land of the occupier.
No representative of G4S was available for comment.
See Adameer's video on G4S' role in Israeli security below.