Billionaire benefactors Bill and Melinda Gates, co-founders of one of the world's largest private charitable foundations, filed for divorce on Monday after 27 years of marriage, saying they had reached an agreement on how to divide their assets.

In a joint petition for dissolution of marriage filed in King County Superior Court in Seattle, the couple stated: "The marriage is irretrievably broken."

But the foundation said Bill Gates, 65, who co-founded Microsoft Corp (MSFT.O), and Melinda Gates would continue to work together in their existing roles as co-chairs and trustees of the organization.

The divorce filing, which states that the couple have no minor children, comes after the youngest of their three children is believed to have recently turned 18. The spouses asked the court to approve their agreement on division of assets but did not disclose details.

"After a great deal of thought and a lot of work on our relationship, we have made the decision to end our marriage," the two said in a statement posted on each of their individual Twitter accounts.

"We no longer believe we can grow together as a couple in the next phase of our lives. We ask for space and privacy for our family as we begin to navigate this new life," they said.

Launched in 2000, the nonprofit Bill & Melinda Gates Foundation ranks as the largest private philanthropic foundation in the United States and one world's biggest, with net assets of $43.3 billion at the end of in 2019, according to the latest full-year financials shown on its website.

From 1994 through 2018 Gates and his wife, who is 56, have provided gifts of more than $36 billion to the Seattle-based foundation, the website said.