Star Wars icon Carrie Fisher has reportedly suffered a heart attack while aboard a flight from London to Los Angeles.

NBC News, citing two law enforcement sources, said her condition was "not good" after being rushed to hospital upon leaving the flight.

Website TMZ said Fisher - who played Princess Leia in the sci-fi franchise - went into cardiac arrest 15 minutes before the plane landed in LA.

A flight attendant reportedly asked if there were any medical professionals on board and a paramedic, who had been sitting at the back of the plane, headed into first class to help.

The LA Times, citing emergency officials, said the actress had been "in a lot of distress on the flight".

The jet landed shortly after noon in LA and she was taken to hospital.

She had been on a book tour promoting her latest book, an autobiography titled The Princess Diarist, in which she revealed an affair with co-star Harrison Ford.