US cable channel AMC has announced that it has renewed The Walking Dead for a fourth series, but showrunner Glen Mazzara is leaving the zombie thriller.

Mazzara had replaced creator and original showrunner Frank Darabont early in the second season.

In a joint statement, Mazzara and AMC said: "Both parties acknowledge that there is a difference of opinion about where the show should go moving forward, and conclude that it is best to part ways.

"This decision is amicable and Glen will remain on for post-production on season 3B as showrunner and executive producer… AMC is grateful for his hard work. We are both proud of our shared success."