Stephen Fry has hit out at the “outrage mob” culture on Twitter – after quitting the platform and closing his account.

The actor, who was an early adopter of the social network, faced strong criticism after comparing costume designer Jenny Beavan to a “bag lady” when she picked up her BAFTA for Mad Max.

After her acceptance speech and she had left the stage, Fry joked: “Only one of the great cinematic costume designers would come to the awards dressed like a bag lady.”

In a blog post after closing his account, Fry claimed that “too many people have peed in the pool” and slammed “nasty” users.

He wrote: “What fun twitter was in the early days, a secret bathing-pool in a magical glade in an enchanted forest. It was glorious ‘to turn as swimmers into cleanness leaping.’

“We frolicked and water-bombed and sometimes, in the moonlight, skinny-dipped. We chattered and laughed and put the world to rights and shared thoughts sacred, silly and profane.

“But now the pool is stagnant. It is frothy with scum, clogged with weeds and littered with broken glass, sharp rocks and slimy rubbish.

“If you don’t watch yourself, with every move you’ll end up being gashed, broken, bruised or contused.

“Even if you negotiate the sharp rocks you’ll soon feel that too many people have peed in the pool for you to want to swim there any more. The fun is over.”

He added: “To leave that metaphor, let us grieve at what twitter has become. A stalking ground for the sanctimoniously self-righteous who love to second-guess, to leap to conclusions and be offended – worse, to be offended on behalf of others they do not even know.

“It’s as nasty and unwholesome a characteristic as can be imagined. It doesn’t matter whether they think they’re defending women, men, transgender people, Muslims, humanists … the ghastliness is absolutely the same.

“It makes sensible people want to take an absolutely opposite point of view. I’ve heard people shriek their secularism in such a way as to make me want instantly to become an evangelical Christian.”

He added: “I would contend that just one turd in a reservoir is enough to persuade one not to drink from it.

“99.9% of the water may be excrement free, but that doesn’t help. With Twitter, for me at least, the tipping point has been reached and the pollution of the service is now just too much.”