Wikipedia Founder Jimmy Wales has called David Cameron's plan to block internet porn as "absolutely ridiculous".
Speaking to Channel 4 News, Wales said Government plans to force ISPs to block new customers from accessing pornography unless they opt-in "won't work".
It's an absolutely ridiculous idea. It won't work. The software you would use to implement this doesn't work.
He added that, rather than create new rules, police should be given resources to enforce existing laws.
"It's an absolutely ridiculous idea. It won't work. The software you would use to implement this doesn't work," said Wales.
"Additionally when we use cases of a paedophile who's been addicted to child porn videos online, you realise all that Cameron's rules would require him to do is opt in and say, 'Yes, I would like porn please'."
He pointed out criminals hacked into Facebook accounts and that was already illegal. "I can't think of any new laws that would actually help with that. What would help is actual enforcement," said Wales.
He said Governments are spending "billions of pounds, billions of dollars, snooping on ordinary people and gathering up all of this data in an apparently fruitless search for terrorists.
"We should devote a significant proportion of that to dealing with the real criminal issues online - people stealing credit card numbers, hacking into websites and things like that," said Wales.
The recent calls for tighter regulation around Twitter, following a number of rape and death threats to women on the social networking site, have also caught his attention.
Wales said it should be easier to report abuse on the microblogging site, but Twitter should not be regulated more strictly.
"When you think about rules about verbal threats, human society has a long history of rules and laws around this, and those rules and laws are very well thought out. They deal with complicated cases," said Wales.
Twitter needed to do more in the past to give people greater control of the environment by making it easier to complain, and to have people behaving badly exposed, blocked or arrested as necessary.
"But it is not like we don't have a law against threatening people. We do, and people are quite rightly being called up on this," he added.
