London (CNN) -- Internet giants signed up Tuesday to a "zero tolerance" approach to images of child sexual abuse as the British government announced a new, tougher strategy to find and block illegal content.
Google, Yahoo, Microsoft, Twitter and Facebook were among the firms summoned to a meeting on the issue at 10 Downing Street, the prime minister's residence, by the UK government's Department for Culture, Media and Sport.
The summit was called in the wake of two recent UK child murder cases. In each case, the killer had viewed child sexual abuse images and violent pornography on the Internet, sparking calls for action to eradicate such content and protect vulnerable young people.
After the summit, the government said the Internet Watch Foundation -- a watchdog body set up in 1996 -- would have new powers to seek out child sex abuse images, block access to them and remove them.
The watchdog has previously acted after an image of child sexual abuse was reported to it via a hotline. While there are an estimated 1 million unique images of child abuse online, only 40,000 reports are made to the Internet Watch Foundation each year, the Department for Culture, Media and Sport said.
Now, the watchdog will work with a cross-agency government body, the Child Exploitation and Online Protection Centre, known as CEOP, to hunt down such images, the department said.
And the UK's leading Internet service providers -- Virgin Media, BSkyB, BT and TalkTalk -- have agreed to give £1 million ($1.57 million) over the next four years to help fund the new approach.
Tuesday's agreement represents a "fundamental change" in the way child sexual abuse content will be tackled, the Department of Culture, Media and Sport said.
"This will mean more images of child sexual abuse will be tracked down and acted on," said Culture Secretary Maria Miller.
"The abuse of children is absolutely abhorrent -- and that child is further violated every single time an image is circulated and viewed. The IWF and CEOP already do important and valuable work.
"This agreement will mean these organizations will no longer be limited to reacting to reports received. They will now have the remit and the resources to take the fight to the criminals perpetrating these vile acts."
In addition, Internet providers have agreed to introduce by the end of the month special pages to tell users when they try to access a page that has been blocked by the Internet Watch Foundation.
The four main UK Internet service providers will also beef up the parental control options they offer, so that parents can easily restrict Internet access on all devices in their home by the end of the year.
The main cell phone service providers in the United Kingdom also took part in the talks.
All the firms present signed a statement saying: "We have a zero tolerance approach to the presence of child sexual abuse material on the Internet."
Prime Minister David Cameron, speaking to reporters at the Group of Eight summit in Northern Ireland, said he was "personally committed" to the battle.
He said he welcomed steps to make sure the big Internet companies "use their expertise, their brains and their brilliance to get these disgusting images off the Internet much faster."
Tuesday's summit is not the only action taken by Web giants to tackle the scourge of exploitative images online.
Google said Tuesday that it will spend $5 million on an effort to wipe pictures of child sexual abuse from the Web and another $2 million to research more effective ways to find, report and eradicate the images.
Some of that money will go to the National Center for Missing and Exploited Children as well as the Internet Watch Foundation, said Jacqueline Fuller, the director of Google Giving, in a blog post.
The Web giant also is creating the Child Protection Technology Fund to develop more efficient ways to fight child porn, and already works to tag illegal images and prevent them being found elsewhere.