McDonald's fast food chain announced yesterday evening that its CEO Steve Easterbrook has left the company after an intimate relationship with a female employee was revealed.

McDonald's says Easterbrook was "fired from the company" after the board decided it "violated its policy and showed miscalculation by entering into a consensual relationship recently with an employee."

Easterbrook acknowledged the relationship in a staff e-mail from the New York Times and other US media.

The CEO told his staff that the relationship was mutually satisfactory, but acknowledged it violated McDonald's rules.

"This was a mistake. Given the company's values, I agree with the board that it's time for me to leave," he said.

McDonald's did not provide further details on the relationship. Chris Kempinski was appointed to replace Easterbrook, who took office immediately. Kempinski previously served as president of McDonald's in the United States.

Eastbrook, a British businessman, chaired McDonald's in Britain and Northern Europe before becoming CEO and president in March 2015 after a period of poor financial performance.