'Terminator' star Arnold Schwarzenegger is no longer relevant to the series says Christian Bale.

The 'Dark Knight' hero who stars in the upcoming 'Terminator Salvation', claims the fourth film in the series is completely different from when Schwarzenegger first played the Terminator role in 1984.

"'Terminator 2' is the original nightmare of just being pursued that everyone has, by somebody who just will not stop, never stops, doesn't give up," Bale said.

"When you've got someone who looked like Schwarzenegger coming after you it made a big difference but nowadays, it wouldn't really — we've seen so many guys who imitated him and it just became a little passé," Bale told Total Film.

The series no longer needs the 61-year-old California governor "because you can't just keep re-hashing the same plot", the 'American Psycho' actor added.

"Yes, 'Terminator' is known for having this one singular figure of villainy that is constantly pursuing but how many times can you keep on doing it?"

But Bale admits it has been difficult to distance the new film from the image created by Schwarzenegger.

"I don't think anyone really had an interest in just imitating the movies that had come before," he said.

"There was a realisation of: 'Look, the mythology is dead unless we reinvent something, put it in a different world, recreate completely." So obviously that'll be the big question for a lot of people. 'Why don't you have that single figure of villainy coming after you?' But I think if we had it would have been same old, same old and why bother?"