Amazon founder Jeff Bezos, rated the world's wealthiest person, announced on Wednesday on Twitter that he and his wife MacKenzie Bezos were divorcing after a long separation.

“We want to make people aware of a development in our lives,” Jeff Bezos, 54, and MacKenzie Bezos, 48, said in a joint statement posted to Bezos' Twitter feed.

“As our family and close friends know, after a long period of loving exploration and trial separation, we have decided to divorce and continue our shared lives as friends.”

The Bezoses said they felt “incredibly lucky” for their 25 years together and would remain involved with each other as close friends and parents.

“Though the labels might be different, we remain a family and we remain cherished friends,” the statement continued.

MacKenzie Bezos is the author of two books, including “The Testing of Luther Albright,” a psychological novel about the challenges facing a Sacramento, California father and his family after an earthquake.

She was one of the first employees of Amazon at its founding and in 2014 launched Bystander Revolution, an anti-bullying organisation.

The couple, who have four children, met while working at the hedge fund DE Shaw prior to Bezos's founding of Amazon.

Jeff Bezos is rated the world's wealthiest man by Forbes and Bloomberg, with a fortune estimated at around $137 billion.

Amazon this week passed Microsoft to become the world's biggest publicly traded company by market capitalisation.