Google has pledged to deploy an army of 10,000 staff to root out violent extremism and content that endangers children on its video sharing website YouTube.

Writing in Tuesday's Daily Telegraph, Susan Wojcicki, the chief executive of YouTube, which is owned by Google, admits that “bad actors are exploiting” the internet site to “mislead, manipulate, harass or even harm”.

Ms Wojcicki today discloses for the first time the scale of the operation to police YouTube, the world’s second most popular website.

YouTube as well as other web giants including Facebook have come under significant pressure over the availability of terrorist material and propaganda on their sites in the wake of five terrorist attacks in the UK this year.

An official report published on Tuesday by David Anderson QC, the former independent reviewer of terrorism legislation, is expected to highlight the huge problems faced by MI5 in its attempts to monitor thousands of potential jihadi terrorists, many of them radicalised online by hate preachers posting on YouTube and other sites.