A LEADING figure in the pro-independence movement has said he believes UK secret services intervened in the referendum campaign, in response to a suggestion at an SNP event that MI5 manipulated postal ballots and were set to work against nationalists at the general election.

Robin McAlpine, director of left wing think tank Common Weal, who does not believe the vote was rigged, said powerful forces within the UK attempted to "at worst, subvert democracy."

He also called for a new law that would make it illegal for employers to attempt to influence the vote of employees.

The comments were made at a fringe event at the SNP conference in Glasgow at the weekend.

Common Weal, the Electoral Reform Society, Women for Independence and the newly-established left wing Spanish party Podemos shared a platform to discuss the ongoing campaign for Scottish independence and the mood of political engagement.

Following introductory speeches from representatives, audience members were invited to join the discussion. The first delegate called on to speak said "we lost because of postal votes", and that the proportion of no votes among postal ballots was a "mathematical impossibility".

Although the panel attempted to intervene at his first mention of MI5, he continued to speak saying "you need to know about it". He added: "MI5 being involved in our elections, how are you going to stop this happening? What are you going to do about stopping it at the next general election coming up?"

While other panellists ignored the intervention, Mr McAlpine chose to respond, saying: "I don't hold [the view] that the actual result was rigged. What I absolutely hold is of course the secret services were involved, that's what they're for. That's because all power, in London and across the UK, tried to at best influence democracy up here using their power and at worst subvert democracy up here."

He added: "There are places we can do something about this - imagine if your employer told you what your sexuality should be. Imagine if your employer told you what your religion should be. I want a law to make it illegal for an employer to seek to influence the vote of their employees. I know people who were scared by their employer because their livelihood was on the line, it's a disgrace. "

Common Weal, which calls itself a 'think and do tank' working for social and economic equality in Scotland has become an increasingly influential voice in the drive for independence. Nationalist general election candidates Philippa Whitford and Tommy Sheppard sit on its board, while many of the policies it advocates, such as ending Trident and an alternative to austerity, are identical to those of the SNP. Other board members include Cat Boyd, co-founder of Radical Independence Campaign and musician and writer Pat Kane, who sat on the advisory board of the official Yes Scotland campaign.

In 2013, SNP councillors unanimously endorsed the Common Weal vision of a fairer Scotland based on the high tax and expanded public spending Nordic model, following a speech by Mr McAlpine.

Tory MSP Alex Johnstone said: "It seems several months after the referendum significant elements of the SNP have still not accepted the result. To blame outside forces - as even Alex Salmond likes to do - is ridiculous."