Fantasy author Philip Pullman was bombarded with ‘get well soon’ messages after he tweeted that he ‘more or less’ collapsed at the Edinburgh Festival.

The writer of the award-winning His Dark Materials trilogy was at the Edinburgh International Book Festival at the weekend, where he spoke about literature and education.

But after feeling distinctly unwell the 71-year-old cancelled a planning visit on Sunday to the unveiling of a new gravestone for the poet William Blake in London.

Mr Pullman, whose latest novel La Belle Sauvage, came out last year, tweeted: “I'm extremely sorry to have had to miss the unveiling on William Blake's new gravestone. I more or less collapsed in Edinburgh yesterday evening. Many apologies to all Blakeians.”

Mr Pullman’s fans immediately responded on Twitter to wish him a speedy recovery, including former Guardian editor Alan Rusbridger, now Principal at Oxford University college Lady Margaret Hall.

The author, who lives in Cumnor, responded by explaining that he was perhaps taking on too many commitments.

He tweeted back: “Very kind of you - thanks. I just needed to be horizontal for a spell. My body thinks it knows better than me, and it probably does. Much better now.”

And in a message to all his followers on Twitter he updated them: “Thank you so much to everyone who's wished me well after I was taken aback by my own faiblesse yesterday. I just tried to do too much. Must stop and rest occasionally. But thank you, thank you.”

Mr Pullman’s La Belle Sauvage, which features characters introduced in the His Dark Materials category, was a huge publishing hit.

It is the first instalment of a trilogy, and the author has been working on the latest instalment.

Welsh production company Bad Wolf is making a new BBC TV series of His Dark Materials, which will star James McAvoy as Lord Asriel and it is thought some scenes were shot on location in Oxford this summer.

Mr Pullman has suffered ill health in recent years and underwent an operation last year.

At the festival in Edinburgh he told the audience that his love of stories began after singing nursery rhymes with family members as a child.

He added: “Nursery rhymes are so important in giving children a basic feel for language, which is one of fun and enjoyment and delight and playfulness.”