CBS chief Les Moonves has defended axing two of the top stars on its hit drama series CSI.

Both George Eads and Jorja Fox were sacked last week after failing to turn up to work in the midst of a dispute over a pay increase.

"There comes a point where we feel a contract is a contract," Moonves told reporters at the TV Critics Association press tour on Sunday. "We had been having discussions with their lawyers. There were certain veiled threats about their not showing up, and there comes a point where we all have to look out for the future of the network television business."

The 'no-show' tactic has worked in the past for the likes of Brad Garrett of Everybody Loves Raymond and several members of The West Wing cast, but Moonves believes that "this behaviour has to stop."

"I'm sort of old-fashioned," he said. "I believe when you and I shake hands and we sign a deal, it's a deal. ... And if by the fourth episode of the season we had decided that George Eads, we wanted to fire him, guess what? I couldn't pick up a phone and say 'You know what, I want to fire you, but the contract really doesn't matter, so I'm not going to pay you for the other 18 episodes that I owe you.'"

Production on the show's fifth season has been halted while replacements are sought and is expected to resume next week. Moonves added that CSI still remains "on schedule" for its September 23 premiere.