Bill and Melinda Gates have announced their divorce after 27 years of marriage, saying "we no longer believe we can grow together as a couple".

"After a great deal of thought and a lot of work on our relationship, we have made the decision to end our marriage," the pair tweeted.

They first met in the 1980s when Melinda joined Bill's Microsoft firm.

The billionaire couple have three children and jointly run the Bill & Melinda Gates Foundation.

The organisation has spent billions fighting causes such as infectious diseases and encouraging vaccinations in children.

The Gates - along with investor Warren Buffett - are behind the Giving Pledge, which calls on billionaires to commit to giving away the majority of their wealth to good causes.

Bill Gates is the fourth wealthiest person in the world, according to Forbes, and is worth $124bn (£89bn).

He made his money through the firm he co-founded in the 1970s, Microsoft, the world's biggest software company.

The pair both posted the statement announcing their divorce on Twitter.

"Over the last 27 years, 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," it read.

"We continue to share a belief in that mission and will continue our work together at the foundation, but 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."

How did they get together?

Melinda joined Microsoft as a product manager in 1987, and the two sat together at a business dinner that year in New York.

They began dating, but as Bill told a Netflix documentary: "We cared a lot for each other and there were only two possibilities: either, we were going to break up or we were going to get married."

Melinda said she found Bill - methodical it seems even in matters of the heart - writing a list on a whiteboard with the "pros and the cons of getting married".

They got married in 1994 on the Hawaiian island of Lanai, reportedly hiring up all the local helicopters to stop unwanted guests flying over.

Bill Gates stepped down from Microsoft's board last year to focus on his philanthropic activities.

BBC