FRESH allegations of prominent pro-Union supporters appearing to have knowledge of postal vote trends before the independence referendum ballots closed have been received by police investi­gating possible breaches of electoral secrecy laws.

Police began an investigation last Friday on the instruction of the Crown Office into claims that pro-Union campaigners acted illegally by seeing and counting postal votes ahead of polling day.

It was sparked by complaints made about comments by Ruth Davidson, leader of the Scottish Conservatives, on a televised discussion that postal vote "tallies" had been taken in the weeks before the ballot closed at 10pm on September 18.

The allegations of illegal postal vote "tallies" raised concerns the information may have helped inform the No campaign's decision to issue the "vow" of more powers for Scotland from the three main party leaders.

Now police have confirmed they have received another complaint relating to separate comments made on television by John McTernan, a former Labour Party adviser on Scotland who supported Better Together.

In the interview four days before the polls closed, Mr McTernan, a political columnist and former communications director for ex-Australian Prime Minister Julia Gillard, said: "It's important to remember that probably about a fifth of the electorate, and that will be about a quarter of the total turnout, voted already. They have voted by postal vote. Those postal votes are running very strongly towards No. So there's a whole bank of votes in."

Mr McTernan, who was also director of political operations when Tony Blair was Prime Minister, told The Herald his conclusions about postal votes were just "a prediction" coming from "my capacious brain and ability to analyse trends that are clearly there in the electorate".

Writing on Twitter, Mr McTernan added: "A polite warning to the cybernuts who think I stole an election. A question about postal votes gets you blocked. For being boring. And mad."

Asked by The Herald how he reached his conclusions about postal votes, he said: "I'm a political commentator. I am able to make comment about what I understand is going to happen, because I can analyse voting patterns.

"I genuinely do not understand what the issue is about this. It was not a huge leap of science to say the people who voted by post were going to vote No.

"My prediction could have been wrong. It turned out it was right because I am good at my job.

"I am perfectly capable of making an intelligent informed assessment of what is going to happen in an election, and perfectly free to say it on television because there is free speech in the UK. That's it.

"There is no story in SNP cybernat trolls trying to bully and defame individuals on Twitter. I am a big guy, I understand these guys don't like me. They can do what they like. I am free to make comments as a journalist and commentator and I made them."

Scottish minister Humza Yousaf also made reference to indications from "postal ballot sampling", saying they were "positive for Yes" in an interview during referendum coverage two-and-a-half hours after the ballots closed.

"The intelligence we're getting is that in those die-hard, traditional Labour areas the Yes campaign is starting to break through quite strongly," he said. "That's initial postal ballot sampling, all the caveats thrown in, etc., etc.."

The SNP said Mr Yousaf was referring to sampling of postal votes after the ballot had closed.

According to Elections Scotland guidance, referendum and postal ballot agents present at the opening of postal votes "must observe the requirement of secrecy".

Failure to observe the rules is a criminal offence, and is punish­able by up to a year in prison and/or a fine of up to £5,000.