Julia Roberts has revealed a remarkable link to the late Martin Luther King Jr and his wife Coretta Scott King, saying that they paid the hospital bill for her birth in 1967.

The actress, 55, who was born in Smyrna, Georgia, explained the couple made the gesture after her mum and dad befriended the Kings while living in Atlanta and running a theatre school.

Her parents, Betty Lou Bredemus and Walter Grady Roberts, were actors and playwrights who had co-founded the Atlanta Actors and Writers Workshop off Juniper Street in the city in 1963 and couldn't afford the expensive fee.

Julia confirmed the story to US broadcaster Gayle King in a clip showing her in conversation with the journalist last month, which has now been shared online by a fan, after sharing her surprise over researchers unearthing the fact.

'One day Coretta King Scott called my mother and asked if her kids could be part of the school because they were having a hard time finding a place that would accept her kids.

'My mom was like, "Sure, come on over," and so they all just became friends, and they helped us out of a jam.'

It has been reported that a Ku Klux Klan member blew up a car outside one of Julia's parents' plays in 1965 in response to King Jr's daughter Yolanda being cast in a role in which she kissed a white actor.

Interviewer King hailed Julia's parents' decision 'extraordinary' because people didn't see 'little black children interacting with little white kids in acting school' at the time.

Julia, who famously dated Friends star Matthew Perry in the mid-1990s, celebrated her 55th birthday on Friday by sharing a selfie of herself sipping a mug of coffee surrounded by pink and gold balloons.

She captioned the photo: 'Feeling the love and magic on my 55th Birthday! My cup runneth over.'

Julia also previously paid tribute to her husband Danny Moder and their life with their children, 17-year-old twins Hazel and Phinnaeus and son Henry, 15.

'The life that I have built with my husband, [and] the life that we've built with our children, that's the best stuff,' she said. 'To come home at the end of the day, triumphantly, to them.'