Bestselling author Philip Pullman has insisted novels must discuss morality or they will slip into the "trivial and worthless", as the Edinburgh book festival starts.

His comments came as fellow author and speaker Fay Weldon dismissed the "chick lit" genre as "done out" and "instantly forgettable" in a serious start to the literary festival.

You can't leave morality out unless your work is so stupid and trivial, and so worthless that no-one would want to read it anyway

Philip Pullman

Pullman, whose award-winning trilogy Dark Materials has been described as children's books for adults, previously ran into trouble with church leaders for his depiction of an alternative world, ruled by an unpleasant God.

Atheist Pullman said English novels had veered away from discussions of morality, death and religion.

"Fantasy and fiction in general is failing to do what it might be doing," he was reported as saying in The Guardian.

"It has unlimited potential to explore all sorts of metaphysical and moral questions, but it is not doing that.

"You can't leave morality out unless your work is so stupid and trivial, and so worthless that no-one would want to read it anyway."

Weldon also contributed to the serious tone of the start to the book festival by telling her audience that "chick lit" books had had their time.

Fay Weldon is one of the most outspoken female authors

The author, who has written more than 20 books including The Life and Loves of a She-Devil, said: "Women are getting fed up with chick lit. The genre is done out," she said in The Guardian.

Helen Fielding's best-seller Bridget Jones' Diary is credited with starting a wave of books from young female authors, claiming to portray the relationships and philosophy of modern women.

Forgettable

"Bridget Jones's Diary was one of a kind. What's followed has been more calculated and doesn't spring from the same zeitgeist," said Weldon.

"Most of them are instantly forgettable but perfectly pleasant to read, like magazine articles.

"By their very nature they are anonymous because there is nothing there to grab you. In a way they're not a natural literary growth."

She refused to reveal which authors had most irked her, and said: "I can't name names, because I simply can't remember them."

This year's Edinburgh film festival also looks set to hit headlines, with the upcoming exhibition of a short animated film by an Israeli director.

Promised Land features a Palestinian suicide bomber rapping on a bus about the rewards that await him in heaven.

It might be shown in Israel or Palestine one day when everything calms down

Gili Dolev

Other vignettes within the 15-minute film include Eitan, a racist thug who attacks elderly Arabs, and Gaddi, an Israeli soldier who shrugs his soldiers when a child is killed in crossfire.

The film, with a number of voices recorded by British comedian Omid Djalili, is considered too controversial to show in the Middle East, but is being exhibited at festivals in the West.

'Listen'

Director Gili Dolev, who moved to Scotland in 1998, has risked the disapproval of his family back in Israel, and is reportedly not allowing himself to be photographed at the festival.

He told the Sunday Herald newspaper: "I know films don't change the world and I know no-one is willing to listen both in Palestine and Israel.

"It might be shown in Israel or Palestine one day when everything calms down."

Meanwhile, bad weather dramatically reduced attendance at Edinburgh's Fringe Sunday, a free event featuring a selection of acts from around the Fringe.

The torrential downpour helped reduce attendance to an estimated 40,000, with most cramming themselves inside comedy, dance and other performance marquees to avoid the rain.

This was a major drop from the previous year's event, held in brilliant sunshine, which organisers said had attracted 150,000.