Saudi Arabia's ambassador to the United States, Prince Turki al-Faisal, has resigned from his post and has left Washington.

Prince Turki reportedly made the announcement to his staff in Washington on Monday, citing personal reasons.

The prince held the post for a year-and-a-half, succeeding Prince Bandar bin Sultan, who left for personal reasons after 22 years on the job.

The Washington Post newspaper says colleagues of Prince Turki said they were shocked at Monday's announcement.

The newspaper also says the departure comes as his brother, Saudi Foreign Minister Prince Saud al-Faisal, is in ill health, noting rumors that Prince Turki could be a possible replacement for Prince Saud.