US network Fox is developing a television series based on the popular "Rambo" movies, with Sylvester Stallone -- who originally starred as a Vietnam war veteran -- on board as an executive producer.

The new series will "explore the complex relationship" between John Rambo and his son JR, a former Navy SEAL, a spokesman for the network told AFP, confirming a story originally reported by Hollywood industry journal Variety.

Fox has ordered a script for the show, called "Rambo: New Blood," which would be a one-hour drama if picked up by the network.

The script was written by Jeb Stuart, who wrote the screenplays for "Die Hard" and the 1993 film version of "The Fugitive" starring Harrison Ford.

The Fox spokesman said casting decisions for the show had not yet been made.