Right-wing extremists have threatened to tear their opponents "limb from limb" during protests due to be held in the Capital on Saturday.
The online threat was made by a member of an English group called North West Infidels, whose members are expected to travel to the Capital on Saturday to take part in a rally organised by the Scottish Defence League.
The NWI's opponents say they are even more radical than the Scottish or English Defence Leagues. On a Facebook page set up by NWI members, a threat has been posted referring to a "coalition" of three groups - themselves, a similar group known as the North East Infidels, and the SDL. It reads: "With only three days left we are issuing a challenge to any Red scum that are planning to oppose us. The NWI-NEW-Sdl coalition thrive on kicking the s*** out of c**** like you so the more of you that turn out in Edinburgh the better, that's more of your scruffy little bodies to go round for us to systematically tear limb from limb. See you Saturday."
The logo on the page proclaims that the group is "A realist, not silent, but possibly violent".
The organisation is thought to be a splinter group from the English Defence League, and its members were reportedly involved in violence in April when they clashed with EDL members during a protest in Blackburn, Lancashire. Other groups have been set up on Facebook for a range of Infidel branches across England.
The SDL vowed to hold a "static" rally in Edinburgh on Saturday after the city council denied it permission to hold a march.
A group called United Against Fascism is planning to hold two counter-rallies with speakers including Malcolm Chisholm, MSP. The first of the rallies will be at The Mound at 11am, with a second by the Wellington Statue at the east end of Princes Street about an hour later.
UAF organiser Luke Henderson called on the authorities to prevent the right-wing groups from gathering in the city at all. He said: "Comments like that demonstrate the vile, racist thuggery of these types of groups and we believe the council and police should not allow them to even assemble, because it's a public order threat."
Assistant Chief Constable Iain Livingstone has pledged to take "a very firm line" if disorder breaks out in the Capital during the protests.
A Lothian and Borders Police spokesman said of the latest threat: "As a matter of routine we monitor social media sites, and we take particular interest in messages that incite violence, encourage disorder, or which issue threats to individuals or groups. In those circumstances we will carry out inquiries and where evidence is obtained we will report offenders."
Thanks to NewsHound and Zaahid for the heads-up