The United States has snubbed a widespread agreement struck at the Christchurch Call to Action in Paris today to eliminate terrorist and violent extremist content online.

Seventeen countries, the European Commission, and eight major tech companies have signed up to the accord.

But in a blow to the strength of the mandate, the United States has chosen not to sign despite extensive diplomatic efforts and the fact that a representative was in Paris at a parallel meeting of G7 Digital Ministers.

However, the White House will not sign the agreement amid US concerns that it clashes with constitutional protections for free speech.

One News Europe correspondent, Joy Reid, told Mike Hosking it has released a statement, offering moral support.

"The Prime Minister and also President Emmanuel Macron seemed quite encouraged by the US approach, by the statement of their support. So they are certainly hopeful that the US might come onboard."

The call is the culmination of weeks of intensive work across many government departments, involving thousands of officials to draw up the document and garner global support just two months after the terror attack.

While it is a voluntary framework, it has been given additional heft after an endorsement from 55 investor funds that will use its $5 trillion in assets to push the tech companies to follow through on their pledges.

And five major tech companies have released a series of commitments, including regular publishing of transparency reports about detecting and removing terrorist or violent extremist content on their online platforms, to strengthen the Call to Action.

They also agree to establish incident management teams to urgently respond to objectionable content.

Facebook has also announced it will be making a number of changes in relation to live-streaming, including banning certain accounts from using the live function.

Facebook's Nick Clegg said that had those rules been in place, the alleged Christchurch mosque shooter wouldn't have been able to live-stream his attacks.