Stating that militant outfits like al Qaeda and ISIS are using internet and social media to radicalise people, the White House has urged technology companies to come out with ways to end what it described as "terrorist safe havens in cyber space".

"We don't want terrorists to have a safe haven in cyberspace," White House Press Secretary Josh Earnest told reporters at his daily news conference a day after US President Barack Obama made a similar appeal.

"Social media sites like Facebook and Twitter recognise that their tools were created in the context of an open society, and the kind of atmosphere that allowed them to innovate and to create new technologies that have allowed people to establish relationships even if they're divided by time and space, is powerful and is successful only in the context of an open society," he said in response to a query.

"They have a responsibility that they obviously believe strongly in, which is protecting free speech, but, you know, these are the kinds of discussions that the Obama administration and technology companies, particularly social media companies, have been engaged in for some time now," the White House spokesman said without going into details of the nature of the talks.

Earnest said there are some terrorists or potential terrorists, would-be terrorists, who are exploiting encrypted technology to prevent government from being able to have access to their information.

"The point that we've made here is that the president believes strongly in good encryption and strong encryption, that that is important to protecting our civil liberties. At the same time, the people who have designed these communications tools, certainly didn't design them to aid and abet a terrorist," he said.

"So, there should be common ground that the government and technology companies can find to address this concern and to make sure the American people are safe," he added.

Earnest said there is an obvious interest that the technology companies have in countering that incitement.

"There is a way for the government and our law enforcement and our homeland security professionals to work effectively with technology companies to essentially to do both, to protect free speech, but at the same time, prevent and counter the efforts of extremist organisations to use social media to incite people to carry out acts of violence," he said.

Responding to a question, Earnest acknowledged that ISIS has been successful in radicalising people through the internet and social media.

"The way that this threat has evolved is that ISIL has proven to be a particularly effective radicaliser, an inspirer of violence. Certainly not the first one, but they are the latest iteration of it. And they do have an effective strategy for propagating their hateful ideology in a way that seeks to inspire people to carry out acts of violence," he observed.

While this is not a new threat, but it is more serious, because ISIL now appears to be more effective than some other organisations that have attempted to do the same thing.

"We are mindful of that threat. And I think, again, this is the reason the president ordered military action in Iraq and in Syria in the first place, is to prevent ISIL or to kick ISIL out of the safe haven that they've established in this part of the world," he said.

"By having a safe haven it makes it easier for them to devise these online strategies. And if we can apply additional pressure to them, take out ISIL leaders, we can be effective in countering their ability to spread that ideology online," Earnest said.