
Associated Newspapers today confirmed his departure, pointing out that there is no replacement currently lined up.
Hart, who joined the group six years ago, led the acquisition of several digital businesses and oversaw the launch of a handful of property and motoring websites such as motors.co.uk.
His departure is the first step in a restructure at the company. Associated said it had mutually agreed to part company and that Hart will leave with immediate effect.
Kevin Beatty, group managing director of ANL, said Hart should be given the recognition for having helped assemble a very strong, robust set of dynamic businesses.
Associated Newspapers’ digital business has thrived in recent months. It is setting up a specialised digital sales unit for Mail Online. And in June, Mail Online leapfrogged Telegraph.co.uk and Guardian.co.uk to become the UK's most popular newspaper website.
According to May ABCe data, Mail Online attracted 18.7 million users, up 3.7% from the previous month.