The cast of the 'Big Bang Theory' want a payrise.

The stars of the CBS show are demanding bosses agree to pay them $1 million per episode before they will sign their contracts for the upcoming eighth season.

Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg and Kunal Nayyar are currently in negotiations with Warner Brothers TV as they are determined to receive a similar wage to the cast of 'Friends', which came to an end in 2004, according to Deadline.

It is believed Jim, Johnny and Kaley all currently earn a reported $325,000 per episode, but bumping their pay up would make them the highest paid actors on US television, beating the likes of Ashton Kutcher and Jon Cryer from comedy 'Two and a Half Men'.

Meanwhile, the eighth season is expected to go into production later this month, but filming could face weeks of delay if an agreement on wages isn't reached soon.

However, the network recently announced that the long-running programme will continue for another three seasons, which means it will stay on screens until at least 2017, after proving to be such a hit with viewers.