Trust in social media companies such as Facebook and Twitter has reached a new low, a major credibility survey has warned, over concerns they do not do enough to tackle bullying, illegal activities and the spreading of extremist content on their sites.

Most people think the online companies are not regulated enough (64 per cent) and lack transparency (63 per cent), according to the Edelman Trust Barometer.

Just over half (57 per cent) believe social media firms take advantage of users' loneliness and 62 per cent think they are selling people's data without their knowledge.

A third (34 per cent) do not think social media is a force for good in society, the survey of 33,000 people found.

Facebook, Twitter and other online giants have faced intense criticism from MPs over the way they deal with offensive or extreme content and the Government has warned they face penalties if they refuse to tighten up controls.