The UK will struggle to block British-born Islamist insurgents from posting on sites such as Facebook and Twitter because very few posts break guidelines on the social networks, according to people who have been monitoring the rise of the Islamic State in Iraq and Syria (ISIS).

Earlier today, the prime minister's spokeswomen claimed 15,000 items of "jihadist propaganda" have been removed from the internet due to government pressure. She also said it was trying to remove a recruitment video, There's No Life Without Jihad, that featured three British fighters.

However Western governments are often unable to stop Islamist fighters posting and discussing about their experiences online because most posts do not violate the rules on sites such as Facebook and Twitter. Even when they do, users can easily open new accounts.

A number of ISIS fighters have active and personable accounts on various social media platforms, such as Twitter, Facebook and Ask.fm and many foreign fighters tweet images of cats, tea and even Coca Cola cans, said Aymenn Jawad Al-Tamimi, a Shillman-Ginsburg Fellow at the Middle East Forum.