She has long been admired as a strong, single woman who raised a young family on her own. But now Diane Keaton has admitted that she would have preferred to have had a man by her side after all.

The Annie Hall actress said she loves being a mother but that the "best possible scenario" would be if she was attached. She also revealed that the older she gets, the more she appreciates life and refuses to slow down.

However, she won't rule out plastic surgery to improve her appearance — even though she looks far younger than her 66 years.

Keaton has dated a string of Hollywood stars, including Woody Allen, Warren Beatty and Al Pacino, but never got married. In 1996, at the age of 50, she adopted daughter Dexter, now 16, followed by son Duke, 10, in 2001.

That year she revealed that she was giving up romance and said she was happy being single.

She now admits that, on hindsight, it would have been better if she had been in a relationship after all.

Keaton said in an interview: "As a parent I provide all I can, but I think in the best possible scenario you need to have a man."

Asked what stopped her from marrying, she said: "I think it was just my whole life. How I responded first to boys and then to men. It had nothing to do with reality. Relationships are hard. You're lucky if you find someone."

Keaton added that even though she is in her sixties, she "never understood the idea that you're supposed to mellow as you get older".

She said: "Slowing down isn't something I relate to at all. The goal is to continue in good and bad, all of it. The best part is that I'm still here and, because the end is in sight, I treasure it all the more."

Keaton won an Oscar for her role in 1977's Annie Hall, which was directed by Allen. In the interview with US magazine AARP, Keaton said that despite her age-defying looks, she would not rule out cosmetic surgery.

She said: "I haven't had it, but never say never. Because when you do, you are definitely going to go there. I said I would never get physically intimate with someone before I was married, and I did. I said I would never go to a psychiatrist, and I spent much of my life in psychoanalysis.

"I've done all kinds of things I said I wouldn't do and, of course, now I'm glad. Thrilled."

Her comments are surprising, given what she has said in the past about her relationships.

In her memoir released last year, called Then Again, she wrote about how she "never found a home in the arms of a man". She also opened up about motherhood and said it was more fulfilling than any relationship she had ever had.

She said: "I'm sorry, but it's better than any of your fantasies about love ... it is love. That's the best thing."

She also wrote that her favourite lover was Woody Allen because she adored his thick glasses and his "great body".