YouTube, a video-sharing website, has pledged to deploy an army of 10,000 staff next year to review more online videos and delete extremist material.
Susan Wojcicki, the chief executive of YouTube which is owned by Google, wrote in the British Daily Telegraph newspaper on Tuesday, saying that "bad actors are exploring" the internet site to "mislead, manipulate, harass or even harm".
YouTube and other internet giants, including Facebook, have come under pressure over the availability of extremist material and propaganda in the wake of five terrorist attacks in Britain this year.
Wojcicki claimed that her company has already developed "computer-learning" technology that can identify videos containing extremist content.
Since June, YouTube's enforcement teams have reviewed two million videos, of which 150,000 have been taken down, she said. Some 98 percent of videos that were removed were initially flagged by the "machine-learning algorithms".
Almost half were removed within two hours of upload and 70 percent within eight hours, according to her.
Those videos included posts by jihadists sympathetic to the Islamic State of Iraq, known as ISIL or IS, and other Islamic terror groups as well as by far-right extremists.
Bomb-making instructions for a device similar to the one used by Slman Abedi, the Manchester Arena bomber, were removed from YouTube in the wake of atrocity, which killed 23 people in the suicide attack on a packed concert in May, the newspaper said.
However, unlike what has been claimed by Google, the bomb-making YouTube tutorial used by Abedi is available on Google networks again, despite being deleted in the wake of the terrorist attack, according to a report by another British newspaper the Sun.
The full 30-minute clip, entitled "Explanation of How to Slaughter Disbelievers", has been shared thousands of times on Google Drive and Google Photos after being re-uploaded to the network on Nov. 22. It was still available to view on Monday night, according to British media reports.