Microsoft co-founder Bill Gates and wife Melinda are to divorce after 27 years of marriage.

The billionaire couple, who have also run the world’s largest charitable foundation, said they would continue to work together at the Bill & Melinda Gates Foundation.

In identical tweets on Monday (US time), they said they had decided to divorce.

“We have raised three incredible children and built a foundation that works all over the world to enable all people to lead healthy, productive lives,” they said.

“We ask for space and privacy for our family as we begin to navigate this new life.”

The couple’s children, Jennifer, Rory and Phoebe, are aged 18-25.

Tweet from @BillGates

However, celebrity gossip website TMZ is reporting that Ms Gates initiated the divorce, filing official paperwork that describes her marriage as “irretrievably broken”.

According to TMZ, it appears the couple have already separated and there is no prenuptial agreement.

“That’s because, according to the filing, the only written agreement that they say pertains to the divorce is the separation agreement,” the website said.

Ms Gates, 56, is not seeking spousal support.

Ms Gates wrote about her childhood, life and private struggles as the wife of a public icon and stay-at-home mother with three kids in her 2019 memoir, The Moment Of Lift.

“When people can’t agree, it’s often because there is no empathy, no sense of shared experience. If you feel what others feel, you’re more likely to see what they see,” she wrote.

“Then you can understand one another. Then you can move to the honest and respectful exchange of ideas that is the mark of a successful partnership. That’s the source of progress.”

Some reports put the Gates’ combined wealth at as much as $US130 billion ($170 billion). Ms Gates also tackled the issue of wealth in her book.

“Great wealth can be very confusing. It can inflate and distort your sense of self – especially if you believe money means merit,” she wrote.

The couple met after Ms Gates began working at Microsoft as a product manager in 1987.

She won the Microsoft co-founder’s heart after meeting him at a work dinner, sharing a mutual love of puzzles and beating him at a maths game.

The couple were married in 1994 in Hawaii.

Their sprawling Seattle-based foundation is easily the most influential private foundation in the world, with an endowment worth nearly $US50 billion ($64 billion). It has focused on global health and development and US education issues since incorporating in 2000.

Mr Gates, 64, once the world’s richest person, was Microsoft’s CEO until 2000. Since then has gradually scaled back his involvement in the company he started with Paul Allen in 1975.

He transitioned out of a day-to-day role in Microsoft in 2008 and served as chairman of the board until 2014.

In 2020, he said he would leave the board to focus on philanthropy.

The Gateses will be the second high-profile Seattle-area billionaire couple to end their marriage in recent years.

Amazon CEO Jeff Bezos and MacKenzie Bezos finalised their divorce in 2019.

MacKenzie Scott has since remarried and now focuses on her own philanthropy. She received a 4 per cent stake in Amazon, worth more than $US36 billion ($46 billion).

-with AAP