Image caption The Simpsons is the longest-running comedy series on US TV and is currently in its 23rd series

US TV network Fox has said it can no longer afford to produce long-running animated comedy The Simpsons without a pay cut for its cast.

In a statement, it said although the series "can and should continue", it could not produce future seasons "under its current financial model".

Fox made the comment after reports it threatened to end the series unless its voice actors took a 45% pay cut.

The cast reportedly earn $8m (£5.2m) each per series.

US news website The Daily Beast reported that the principal voice cast members, including Dan Castellaneta, Julie Kavner, Nancy Cartwright and Yeardley Smith, were having difficulty agreeing contracts for the next series.

It said the cast had unsuccessfully tried to negotiate a 30% pay cut in return for a percentage of the show's profits from syndication and merchandising.

Fox added in its statement: "We are hopeful that we can reach an agreement with the voice cast that allows The Simpsons to go on entertaining audiences with original episodes for many years to come."

Simpsons channel?

The show has a long history of pay disputes between the cast and Fox.

The network threatened to replace the cast in 1998 after they asked to bump up their salaries from $30,000 (£19,500) to $125,000 (£81,000) per episode.

In 2004 production was halted for a month after another dispute in which voice actors asked for around $360,000 (£233,000) per episode.

THE SIMPSONS FACTS Began life as an animated short on The Tracey Ullman Show in 1987

Creator Matt Groening named the characters after members of his own family

First half-hour episode broadcast on Fox on 17 December 1989

488 episodes broadcast to date

Longest-running primetime animated series and longest-running sitcom in the US

Three years ago, the show was delayed again for several months after contract negotiations stalled over a new four-year deal which eventually saw cast members' pay packets increase to $400,000 (£259,000) each an episode.

The Simpsons - currently in its 23rd series - is the longest-running comedy series on US television and is broadcast in more than 100 countries and 50 languages.

However ratings for the current series in the US have averaged 7.1 million viewers, down 14% from last year.

At a recent media conference, the chief operating officer of News Corp - which owns Fox - said the company was looking at ways to increase revenue from the animation.

Chase Carey said there had been discussions about the possibility of setting up a Simpsons cable channel in the US, devoted to showing repeats of the show.

But he added: "We haven't drawn up any plans for a Simpsons channel. But there are a lot of Simpsons fans out there. It's a real opportunity for us to do something truly unique."