Policing needs to be assessed ahead of next year's general election following intimidation and attacks on freedom of speech at Scottish referendum events, MPs have heard.
Commons Leader William Hague said it was "disgraceful" to see people heckled while giving their views in the referendum debate, while Labour's John Robertson claimed pro-independence campaigners were responsible for the worst "intimidation" he had seen in his political life.
Mr Robertson, MP for Glasgow North West, added "freedom of speech has been attacked" as he called for a Westminster debate to discuss policing during the election and referendum campaigns and vote.
Labour MP Jim Murphy temporarily suspended his pro-Union 100 Streets In 100 Days tour amid claims that the events were being targeted by Yes supporters in a co-ordinated campaign, while Scottish First Minister Alex Salmond was involved in a "road rage" incident in which he was chased in his car by someone waving a No sign at him.
Speaking in the Commons, Mr Robertson told Mr Hague: "We have seen north of the border intimidation like I have never seen in my time being involved in politics by the Yes campaign, which was seen when (Mr Murphy) was attacked while not only speaking but protecting an elderly lady.
"Freedom of speech has been attacked. I think we need to look at it again and make sure with the general election next year and a possible referendum, when things will be riding high, we need to look at these to make sure the intimidation that is happening... (does) not happen."
Mr Hague replied: "You raise a disturbing and important point. You are quite right to point out the importance of free speech, something all of us in all parties have always been very proud of in the United Kingdom - that in an election campaign or a referendum campaign, whatever our disagreements, we listen to each other.
"That is one of the great qualities of the UK compared to many other countries in the world. It's something we should always be proud to uphold.
"It has been disgraceful to see members of this House or indeed anyone else heckled or attempts to drive them out from giving their views in the referendum.
"You are quite right to draw attention to the need to uphold free speech."