The government wants ISPs to block access to pornography websites, so web users do not need to rely on parental controls to ensure children are not exposed to inappropriate content when surfing the web.

Culture minister Ed Vaizey is to meet with ISPs including Virgin Media, TalkTalk and BT "in the near future" to discuss the plans.

Vaizey's plans, which follow moves by UK ISPs to block access to all websites containing child pornography images, also include the ability to 'opt-in', which means web users will have to request access to specific sex-related sites.

"This is a very serious matter. I think it is very important that it's the ISPs that some up with solutions to protect children," Vaizey told The Sunday Times.

"I'm hoping they will get their acts together so that we don't have to legislate, but we are keeping an eye on the situation and we will have a new communications bill in the next couple of years."

A number of ISPs said implementing the scheme would be technically challenging and expensive. However, executive director of strategy and regulation at TalkTalk, Andrew Heaney, told the Sunday Times: Our objective was not to do what the politicians want us but to do what is right for our customers. If other companies aren't going to do it of their own volition, then maybe they should be leant on".

Meanwhile, Virgin Media revealed it already offers an opt-in function when surfing the web from mobile phones.

"We're able to block sites, so it would be possible to do the same on the internet. It is just about finding the right approach," a spokesman said.

During a recent parliamentary debate, Claire Perry, Conservative MP for Wiltshire, called on the government to put pressure on ISPs to block pornography websites, citing information from Psychologies magazine that showed 60 per cent of nine to 19 year olds admitted they had found porn online (though we couldn't find this report on the Psychologies web site and research cited by the magazine's 'Put Porn In Its Place' campaingn extended only to one group of 14-16 year olds at a North London school).