Production on the new season of The Big Bang Theory is being delayed due to a contract dispute with some of its stars.

Warner Brothers Television studio, which makes the popular sitcom about four super-nerds in the US, said the scheduled first day of work on Wednesday after the summer hiatus has been postponed.

The series is heading into its eighth season, and the studio is trying to hammer out new deals with actors Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg and Kunal Nayyar.

Contract disputes are not unusual on popular, long-running U TV series.

It is unclear how long the dispute would have to last before it would cause a delay in episodes getting to air.