The new Ghostbusters film will go ahead without the involvement of Bill Murray, according to his franchise co-star Dan Aykroyd.

Murray said in June that he turned down the chance to star in Ghostbusters 3 because the screenplay was not up to scratch. Aykroyd, who has been spearheading efforts to bring the series back to the big screen, said the film would now progress without him.

"We've got a brilliant new writer on it and we'll be passing the torch on to a new generation," Aykroyd told Metro. "We're working on it to make it just right to satisfy our fans. I'm confident we'll be in production in the next year."

He added: "It's sad but … Ghostbusters 3 can be a successful movie without Bill. My preference would be to have him involved but at this point he doesn't seem to be coming and we have to move on. It's time to make the third one."

Murray told David Letterman in June that he wanted any new Ghostbusters film to be as funny as the 1984 instalment which launched the series, rather than its poorly received 1989 sequel.

"They just don't have a really good script," he said. "It's hard. You know, even the second Ghostbusters wasn't as much fun for me as the first one. It's hard to make a sequel. That first one was so darn funny. It's hard for me."

Ghostbusters 3 was at one point expected to shoot last May, with Murray himself appearing in character as Peter Venkman at the 2010 Scream awards, suggesting he had warmed to the idea. Harold Ramis, who played Egon Spengler in the 80s films, was set to direct and co-star, with Aykroyd reprising his role as Ray Stantz. The latter described Murray's proposed return as the "comic role of a lifetime".

In August last year, Aykroyd appeared on the Dennis Miller show and appeared to hint that the film might go ahead without Murray. However, in February he said he was unsure if a third film would ever now be made, since his former co-star was not interested.

The new writer for Ghostbusters 3 is believed to be Etan Cohen, who oversaw the screenplays for Men in Black III and Tropic Thunder. According to reports, the new supernatural pest control quartet will include at least one woman.