Westbrook first appeared in EastEnders in 1990
Danniella Westbrook is to leave BBC One soap EastEnders, where she plays Sam Mitchell, by the end of the year, the show's spokesman has confirmed.
Her departure will come as her storyline ends and not as a result of the actress's contract being cut short as was reported in weekend tabloids.
"Danniella was brought back to EastEnders for a specific storyline and a set amount of time only," said the spokesman.
Viewers saw Westbrook return last week.
She had been out of the show for nine years, although the character of Sam Mitchell has been played by actress Kim Medcalf in the interim.
Sam Mitchell's return saw her fly in from Brazil, where she fled after being implicated in the murder of "Dirty" Den Watts. She has since been arrested.
The BBC spokesman continued: "We are not going into the exact details [of Westbrook's departure] as we don't want to spoil the storyline for our viewers but Danniella's contract has not been cut short - in fact it has been extended slightly.
"We have been thrilled with how Sam Mitchell's return has been received with our audience and hope that they continue to enjoy her storylines over the next few months."
The door would "remain open" for Westbrook to return in the future, the spokesman added.
The actress, 35, first appeared on Albert Square in 1990 but left in 1996. She spent a brief second stint in the show between 1999 and 2000.
In 2002, she was replaced by Medcalf, who left EastEnders in 2005.