OPPOSITION figures have raised concerns the Scottish Government is “rigging the rules” of a future independence referendum.

Scottish Tory MSPs accused ministers of an “inappropriate” attempt to exclude the independent Electoral Commission from the process of deciding the question to be put to voters.

It follows an ongoing row over whether the watchdog should re-test 2014's Yes/No question.

The SNP want to keep this format, while some opponents favour a Leave/Remain option because of its toxic echoes of Brexit.

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The issue was reignited once again at Holyrood’s Finance and Constitution Committee, which is scrutinising the Referendums Bill, the legislation setting out the framework for any future referendum.

Constitutional Relations Secretary Michael Russell tabled amendments which would limit the use of any question to the lifetime of the parliament which approved it - meaning no more than five years in practice.

However this “validity period” could be extended to two parliamentary terms for a previously approved question if MSPs voted in favour of such an extension.

This would still allow the Yes/No question of 2014 to be re-used in 2020 – when Nicola Sturgeon wants to hold a second vote – without the Commission testing it, but only if Parliament approved.

Scottish Tory MSP Adam Tomkins criticised the move as “inappropriate and premature”, as the Commission has not agreed to it.

He said: “This is one of the most important issues raised by the Bill, and the reason why it’s important is because referendums decide things, and they decide big things – things that matter, things that change the entire nation.

“And it is surely something that we should all want to agree with, that the ground rules for setting up referendums must be unimpeachable.

“The First Minister herself has referred to the 2014 independence referendum as the gold standard.”

He added: “There is a lingering suspicion that seeking to bypass the independent statutory function of the Electoral Commission, or seeking to minimise the independent statutory function of the Electoral Commission is rigging the rules of a future referendum.

“There is a very clear three-way relationship…ministers propose referendum questions, the Electoral Commission independently tests the intelligibility of those questions and then Parliament decides.

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“That should happen for every referendum in the United Kingdom, or in any part of the United Kingdom.”

Scottish Tory MSP Murdo Fraser also branded Mr Russell’s amendments “premature”.

He added: “They are putting the cart before the horse, because we do not at this point have an agreement with the Electoral Commission.

“And for the Cabinet Secretary to put forward these amendments stating what he wants the position to be, when there’s not been agreement with the Electoral Commission, I think is pushing the boat out too far.”

The Government’s Referendums Bill previously said the Commission must test all referendum questions for fairness and intelligibility.

However it included a controversial exemption for questions which have been previously approved by the Commission, such as that used in 2014.

Mr Russell argues a different question in Indyref2 would only confuse voters.

Giving evidence to the Finance and Constitution Committee, he said his new amendments were a compromise.

He said: “This takes us on, and is a major concession from the Scottish Government, and I think it should be recognised as such.”

Mr Russell’s amendments were voted through, but may come under renewed scrutiny when the legislation comes before Holyrood in its final stage.

The Electoral Commission has said it wants to test all questions, so that it can take into account changes of context and fresh evidence about their suitability.

Elsewhere, a bid by Scottish Labour MSP James Kelly to declare the result of any future referendum invalid if fewer than 50 per cent of voters take part was rejected by MSPs.

Mr Kelly tabled an amendment stating the result of any referendum would be valid “only if the number of votes cast represents a minimum of 50% of the total number of persons entitled to vote in the referendum”.

He denied suggestions he was trying to meddle in any future Indyref2, insisting his amendment would apply to any referendum on any topic.

He said: “Clearly, any future independence referendum, a turn out would exceed 50% – and it’s disingenuous to suggest otherwise.”

He added: “It’s not a question of rigging the rules. It’s a question of ensuring that any outcome has democratic credibility.”

But SNP MSP Angela Constance accused him of “triggering an entire nation back to 1979”, adding: “It’s like the ghost of Christmas past, I’m afraid.”

In the 1979 devolution vote, Labour MP George Cunningham amended the Scotland Act so that any referendum required the approval of 40% of the total electorate.

While 1,230,937 Scots voted in favour of a Scottish Assembly, around 52%, it only represented around 33% of the registered electorate as a whole.

Ms Constance said: “In the context of a referendum on Scotland’s constitutional future, I think this very much is a wrecking amendment.

“I think it is a wolf in sheep’s clothing. I think it is anti-democratic…because it assumes that not voting equates to a support for the status quo.

“I have to say I’m vehemently opposed to this amendment.”