Video manuals about turning everyday products into shrapnel-filled bombs, like that used by the Manchester suicide bomber, are reportedly freely available on social media sites.
One Facebook video seen by the Times recommends soaking nails in vinegar and rat poison in order to make the weapon more lethal.
If the social media giant fails to remove such material after being alerted it could be committing a criminal offence, lawyers told the Standard.
The Times’ investigation found further Facebook videos on bomb-making as well as an 11,000 word guide.
YouTube was also found to be carrying ‘how to’ terrorism guides on bomb-making, with one about ricin poison watched almost 5,000 times before it was removed.
Another video from the series, called Jihadi Ideas for Lone Lions, tells watchers how to make a household bomb using household items such as a coffee filter.
A YouTube spokesperson said: “We take these issues extremely seriously and we work in partnership with the government and NGOs to tackle these challenging and complex problems. On YouTube, we employ thousands of people and invest hundreds of millions of pounds to fight abuse on our platform.
“We act quickly to remove flagged content that incites violence and terminate accounts run by terrorist organisations.”
A Facebook spokesperson said: "There is no place for terrorists or content that promotes terrorism on Facebook and we remove it as soon as we become aware of it. We have reviewed the posts sent to us and removed them as they break our standards.
"Our Community Standards help people understand what is allowed on Facebook and we urge people to use our reporting tools if they find content that they believe violates our standards, so we can continue to investigate and take swift action."
