A referendum on independence could lead to unfair and unbalanced campaigning by political parties if it were called by Holyrood, it has emerged.

A referendum on independence could lead to unfair and unbalanced campaigning by political parties if it were called by Holyrood, it has emerged.

John McCormick, the Electoral Commission's Scottish member, said yesterday that the current election law, passed in 2000, would set clear rules if Westminster calls another national referendum, including a cap on campaign finance, registration of non-party campaign organisations and a register of donors. The Electoral Commission chairman, currently Sam Younger, would be the national referendum returning officer, or he could delegate that role.

But that does not apply to the Scottish Parliament if it calls a referendum, meaning the campaign could be skewed by large amounts of money, without its source being open, allowing one side to dominate the campaign.

With the SNP wanting a referendum in autumn 2010 and with Labour's Holyrood leader, Wendy Alexander, saying she will back one, at least in principle, the rules to ensure a fair fight are far from clear.

But Mr McCormick, who recently took over the Scottish commissioner's role after retiring as controller of BBC Scotland, says the Electoral Commission is willing to step in, if asked to do so.

He says rules for a UK referendum - which could have been used if there had been a vote on the euro or the European Constitution - are clear, and would be treated as enabling legislation for them to apply if the Scottish Parliament requires one. "If they the Scottish Government came to us for help, advice, or to run the referendum, then we would be willing to do that," he explained.

Mr McCormick said Mr Younger's successor as chairman, to be appointed later this year, could delegate responsibility for running the election to his Scottish commissioner. It is less clear whether the finance registration for a UK referendum would have backing for investigation and legal enforcement.

One of the areas of dispute between the SNP and Labour is the wording of the question. Labour wishes to include reference to "leaving the United Kingdom", reckoning that negative framing will be a voter turn-off.

Mr McCormick says it is not for the Electoral Commission to choose the wording, but it is willing to advise. "Based on the legislation, it looks at what is a good question, objectively, and advises on it. The government of the day chooses the question: the Electoral Commission gives its advice."

The 10 guidelines for a referendum question include a requirement that it should not have positive or negative connotations, including the words new, approve, abolish, old and reject, and it should not be intentionally leading or loaded.

The SNP's white paper on independence, published in August, suggests: "I agree/ disagree that the Scottish Government should negotiate a settlement with the Government of the United Kingdom so that Scotland becomes an independent state."