FEARS of "absolute carnage" outside polling stations on Referendum Day amid a growing atmosphere of intimidation have been raised by the No camp.

The suggestion comes after Yes Scotland was accused of organising "street mobbery" to shout down leading Unionist Jim Murphy, who warned the campaign had taken a "sinister turn".

Better Together leader Alistair Darling will talk to Police Scotland this week about the force's plans for September 18 and his "increasing concerns about the temperature of the debate".

Yesterday, a 55-year-old man was charged over an alleged assault on a woman after a disturbance between Yes and No campaigners in Glasgow. The incident involved about 30 people in Argyle Street on Saturday afternoon.The man has been released and a report will be sent to the procurator-fiscal.

Mary Pitcaithly, the Chief Counting Officer overseeing the vote, has spoken to Police Scotland about security and possible "high tensions" with an expected big turnout. Police are said to be planning a huge security operation.

Alex Salmond made it clear he absolutely condemned any intimidation, but said claims of organised mobs were "ridiculous" and emphasised the high level of political engagement among ordinary citizens in the campaign.

Mr Murphy has suspended his "100 towns in 100 days" tour on police advice after he complained of organised intimidation. He was hit by an egg while campaigning in Kirkcaldy.

The MP for East Renfrewshire said passionate engagement, heckling and even egg-throwing were part of the campaign process but orchestrated intimidation by scores of people was not.

"I would turn up and there was an organised mob of Yes supporters, facilitated through the Yes Scotland local organisations, their websites, Facebook and other social media," he explained.

The Labour front-bencher said he had fears for the public, saying: "These are people intending to disrupt and silence undecided voters on street corners so they cannot have their say." He added: "There's a difference between passion and aggression and there's a difference between one or two or even a dozen people turning up to heckle, and hundreds of people being organised to turn up to disrupt their opponents' meetings, turning over tables, climbing onto the crates, trying to attack a photographer because they happened to be English."

Mr Murphy said he had been called a traitor, a Quisling and a terrorist and added: "This isn't about small individuals or the odd idiot, this is orchestrated, it's co-ordinated and it has to stop."

Fears have been expressed of polling-day trouble, with No supporters concerned about intimidation at polling stations when rival campaigners come face to face. One senior No campaign source said: "We are worried that there is going to be absolute carnage."

The First Minister, who is in Dundee today, hailed the campaign as the "most exciting, participative and powerful debate in Scottish political history". He pointed out that someone was convicted last week of making online threats to him, and said a female Yes supporter was assaulted in Glasgow.

But, he said: "I don't hold press conferences accusing Mr Murphy or the No Campaign of orchestrating these events because I know that it would be ridiculous to do so. So let me be absolutely clear … If Mr Murphy comes bawling and shouting at a street corner near you any time soon, keep doing your shopping, go on with what you are doing. It's just like a guy with 'the End is Nigh' round his neck; he'll go away soon."

Both sides urged those who have not yet registered to vote to do so. The deadline for registration is tomorrow.