No-one reported the video of the Christchurch terror attack while it was being streamed live, Facebook has said.

It was 29 minutes after the video had started - and 12 minutes after it had ended - before the first user flagged up the footage, the social media company added.

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A blog post by Chris Sonderby, vice president and deputy general counsel at Facebook, said the video was viewed fewer than 200 times during its live broadcast.

"The video was viewed about 4,000 times in total before being removed from Facebook," he added.

"The first user report on the original video came in 29 minutes after the video started, and 12 minutes after the live broadcast ended.

"Before we were alerted to the video, a user on 8chan posted a link to a copy of the video on a file-sharing site."

Mr Sonderby said Facebook was "working around the clock" to prevent the video from appearing on its site.

Prime Minister Theresa May has said the New Zealand mosque attack and the stabbing of a teenager in Surrey fitted a "pattern of concern" that the threat from the far right was on the rise.

READ MORE: Christchurch shootings: New Zealand cabinet backs tighter gun laws 

Ministers attending the weekly meeting of the Cabinet in Downing Street expressed their sympathies for the victims of the attack in New Zealand.

"The Prime Minister said the terrible attack and the incident which took place in Surrey on Saturday evening fitted a pattern of concern that the threat from the far right is on the rise," the Prime Minister's official spokesman said.

"The Prime Minister said there could be no place for vile extremist views in society and people must be able to practise their faith without fear.

"She said that intensive work was taking place across government and by the police and security services to combat the threat."

Home Secretary Sajid Javid said there was a "real sense of anxiety" among the British Muslim community and that he would be announcing additional funding for the protection of places of worship.