The Hollywood couple, who never married, separated in the summer but have only just announced their break-up.

A spokesperson for the 63-year-old “The Lovely Bones” actress said: “Susan Sarandon and her partner of 23 years, actor Tim Robbins, have announced that they have separated over the summer. No further comments will be made.”

“War of the Worlds” actor Robbins and Sarandon have two sons, 20-year-old Jack and 17-year old Miles. They first met on the set of the 80s movie “Bull Durham.”

Sarandon always insisted she and Robbins never tied the knot because they wanted to keep the romance in their relationship alive.

She previously said: “I won’t marry because I am afraid of taking him for granted or him taking me for granted.”

Sarandon also has a third child, daughter Eva from a previous relationship with film director Franco Amurri.

The “Thelma and Louise” actress – who has sons Jack, 20, and 17-year-old Miles with partner Tim Robbins – says her “sexual” boys were keen to wed their mother and she had to tell them it wasn’t possible.

She said: “If I kissed someone in a film, my son used to ask, ‘Did you have sex in that movie?’ and I’d say, ‘No, we just kissed,’ yet he considered it sexual.”

“But that is the dance, because sexuality exists around children. From the time they’re walking, they’re completely sexual. I remember having to explain to both my sons that we couldn’t get married.”

Susan – who also has a 24-year-old daughter Eva from a previous relationship – also revealed she began to stop doing nude scenes when her children began to ask difficult questions.

The 63-year-old star told Psychologies magazine: “They’ll point out something I did earlier and ask, ‘Did it never occur to you that you might have a child?’ I say, ‘No, it didn’t, really.’ But I accept them; they have to learn to accept me.”

Susan Sarandon has posed semi-naked for a new book.

The actress – who turns 62 tomorrow (Oct 4, 2008) – is pictured lying on her back wearing only fishnet tights and a feather boa in “Hollywood Pinups,” by Timothy White.

Speaking about the photoshoot, Susan said: “What a treat to play in the world of the beautiful, perfect pin-up fantasy.”

The book, which is due for release later this month, also features actresses including Mary-Kate Olsen, Kate Hudson and Molly Sims in a series of racy 1940s-style poses.

The “Thelma and Louse” star – who has two sons with partner Tim Robbins – has previously admitted she enjoys the aging process.

She said: “I actually look forward to getting older – it is certainly better than the alternative – when looks should become less of an issue, and when who you are is the point.”

“I haven’t had any surgery, but I don’t knock it. I think that women, anyone, has the right to do anything that they like with their bodies if it makes them feel good about themselves.”