India - the country that invented sex manual the Kama Sutra - has blocked hundreds of pornographic websites to top adult material becoming a 'social nuisance'.

A government official confirmed today that internet service providers have been told to block 857 websites as part of a crackdown on internet porn.

'Free and open access to porn websites has been brought under check,' N.N. Kaul, a spokesman for the department of telecommunications, said.

Crackdown: The Indian government has asked internet providers to block 857 websites with adult content

'Morality': A government spokesman said that they didn't want the porn websites to be a 'social nuisance', and issued a 17-page order to internet providers to block access on the grounds of decency (file image)

'We don't want them to become a social nuisance.'

The government issued a 17-page order issued on July 31 listing offending sites and telling internet providers to block access on the grounds of morality and decency.

The list was leaked to freedom of speech activists on Monday, and the government was forced to admit its position.

It comes despite a ruling last month by the Supreme Court, who refused to impose an outright ban after hearing a petition that said Internet porn fuelled sex crime. The court said individuals should be free to access such websites in private.

But the court asked the home ministry to submit its views and the government acted after the ministry sent a letter to the telecom secretary, Kaul said.

Over the weekend, several sites became inaccessible and displayed messages that they were blocked on instructions of the competent authority. The hash tag #Pornban became a trend on Twitter.

'Porn ban is anti-freedom, impractical, not enforceable. Politically not very smart too. Avoidable. Let's not manage people's private lives' best-selling novelist Chetan Bhagat posted on Twitter.

Backlash: Since the decision by the Indian government (pictured) people have taken to social media to complain that the porn ban is anti-democratic. The hashtag #pornban began trending on Twitter

India has the second largest number of internet users after China. Social media and smartphone use is growing rapidly.

In 2011, India urged social network companies to screen content and remove offensive material. A year later, the government faced criticism for ordering dozens of Twitter accounts to be blocked for spreading rumours.

Censorship extends to Bollywood and Hollywood movies, with regulators often forcing producers to edit dialogues and scenes to suit audiences in the generally conservative country.

Demand for porn, however, seems strong. Pornhub, an adult entertainment website included in the ban, last year said India ranked fifth for daily visitors.