Ukip has been blasted for "nativism and thinly disguised bigotry" after using The Great Escape music on the Brexit campaign bus, it has been reported.
Elmer Bernstein's inspiring theme tune has apparently been used by Vote Leave on their tour of Britain ahead of the EU referendum on June 23.
The sons of the late composer, Peter and Greg Bernstein, said their father would never have given his permission, according to The Observer.
"Our father would never have allowed Ukip to use his music because he would have strongly opposed the party's nativism and thinly disguised bigotry," they said in a statement sent to the newspaper.
"He would surely say that The Great Escape celebrated those who bravely saved Europe from a horrifically racist, nativist and violent regime," they added.
"He would hardly see Ukip as either a worthy successor of that cause or embodying the spirit of those who liberated Europe from oppression and hatred."
The Hollywood composer had "very strong, mostly liberal" political views and "never allowed his music to be used for political purposes", his sons said.
"He preferred it to remain in the realm of entertainment where it originated, simply for people to enjoy, and not as a vehicle for political messaging," they told The Observer.
The rights to the theme are now owned by Sony ATV, and Vote Leave was unable to confirm whether it had obtained a licence to play it in public, according to reports.
"It plays for about 15 seconds before Nigel Farage speaks," a spokesman told The Observer.
"But I don't know whether permission was asked. Nigel is not on the bus this weekend - other people are using it. But we play a pre-recorded speech from him for a couple of minutes."
Elmer Bernstein was born in New York, worked on Hollywood films for 50 years and died in 2004.