Jeremy Corbyn has said he is “sincerely sorry” for the pain caused by “pockets of anti-Semitism” in the Labour party.
In a statement, the Labour leader said he would be meeting representatives of the Jewish community this week to “rebuild” confidence in his party.
He said Labour was “anti-racist” and he “utterly condemns” anti-Semitism.
The comments came after Mr Corbyn was criticised for sending an apparently supportive message to the creator of an allegedly anti-Semitic mural in 2012.
In a message sent via Facebook, he had appeared to question a decision to remove the artist’s controversial mural. He later called the mural “deeply disturbing” and backed its removal.
Mr Corbyn said: “I sincerely regret that I did not look more closely at the image I was commenting on, the contents of which are deeply disturbing and anti-Semitic.
“I am opposed to the production of anti-Semitic material of any kind, and the defence of free speech cannot be used as a justification for the promotion of anti-Semitism in any form.”
Mear One – whose real name is Kalen Ockerman – has denied being anti-Semitic, saying the mural was about “class and privilege”.
On Sunday, senior Labour figures joined in condemnation of the mural but defended Mr Corbyn.
Shadow transport secretary Andy McDonald told Sky News that Mr Corbyn “hasn’t got an anti-Semitic bone in his body” and that the row had “misinterpreted the intentions of a really good and decent man”.
And Labour’s Shadow Brexit Secretary Sir Keir Starmer said the mural was “grotesque and disgusting” but that Mr Corbyn had given his explanation for his online comment.
Deputy Labour leader Mr Watson told the BBC’s Andrew Marr Show: “I am very, very sorry that people feel hurt by this and that is why I think it is right that Jeremy has expressed regret for it.”
On Friday, Labour MP Angela Smith joined other members in supporting Ms Berger and sent a statement to the Leader’s Office, calling for Mr Corbyn to appear before MPs to explain himself.
Yvette Cooper tweeted that she was “really troubled by the mural” and that “Labour must be better than this”.