Carrie Fisher is in critical condition after a 'cardiac episode' on flight.

Actress Carrie Fisher has been rushed to hospital after suffering a “cardiac episode” on a flight from London to Los Angeles.

The LA Times reports Fisher, 60, was taken to UCLA Medical Centre after the 11-hour flight. The actress was reportedly “in a lot of distress on the flight”.

Medical staff met the actress at LAX after the pilot of United Airlines fight 935 told the control tower nurses were tending to an ‘unresponsive’ passenger.

Carrie Fisher and Harrison Ford in Star Wars: The Force Awakens.

“Our thoughts are with our customer at this time,” a statement from United Airlines read.

Carrie’s brother, Todd Fisher, told the Associated Press that his sister had been stabilised at the hospital but did not provide further details.

Fisher is most famous for her role as Princess Leia from Star Wars and has been touring to promote her book, The Princess Diarist.

Co-stars and fans around the world are flooding social media with messages of support.

Carrie Fisher has written and spoken openly about her struggles in Hollywood. She also gave an insight into the difficult relationship she shares with her mother in the book-to-movie "Postcards From the Edge.” She’s further been outspoken about her mental health issues.

She had been on a tour promoting a new memoir.