The Iraqi government appears to have blocked Facebook, Twitter and other social media, amid escalating combat.

Users in the country attempting to visit these sites are greeted by a message saying the Ministry of Communications has barred access.

The move comes after Islamist insurgents used Twitter to post a graphic image of a beheaded man, and to spread propaganda messages.

A Facebook spokesperson said the block was "a matter of concern".

One source in Iraq said that access to the internet was entirely restricted in some provinces.