Billionaire philanthropist Melinda French Gates has said she will resign as a co-chair of the Bill & Melinda Gates Foundation.

“This is not a decision I came to lightly,” Ms Gates wrote in a statement posted to X on Monday.

Her last day of work will be 7 June.

Ms Gates started the foundation – the largest private body of its kind – in 2000 with her then-husband Bill Gates, the Microsoft co-founder.

In 2021, after 27 years of marriage, the pair announced their separation, but pledged to carry on with their joint philanthropic work. At the time of their split, the former couple said they would remain co-chairs and trustees of the organisation and that no changes to the foundation’s structure were expected.

The Gates Foundation is among the most powerful groups in public health, with an endowment of more than $75bn (£59.7bn) as of December. It spends billions of dollars every year on initiatives aimed at eradicating infectious diseases, reducing poverty and combatting climate change.

According to the foundation’s website, the couple donated more than $36bn (£28bn) of their own wealth to it from 1994 to 2018.

“I am immensely proud of the foundation that Bill and I built together,” Ms Gates wrote in her statement adding that under an agreement with Mr Gates, she will now have an additional $12.5bn for her own charitable work on women and families.

In 2015, Ms Gates founded investment company Pivotal Ventures, a separate entity from the Gates Foundation, which focuses on removing barriers to opportunity for women and minority groups.

“This is a critical moment for women and girls in the US and around the world – and those fighting to protect and advance equality are in urgent need of support,” she wrote in Monday’s statement.

Mr Gates said he was “sorry to see Melinda leave, but I am sure she will have a huge impact in her future philanthropic work”.

The Microsoft founder remains one of the world’s richest men, with a net worth of more than $130.3bn, according to Forbes. Ms Gates’ fortune is listed at $11.3bn.