Alex Salmond struck a slightly more conciliatory tone regarding a Scottish independence referendum on Wednesday morning, suggesting there could be further negotiations with Westminster on the mounting constitutional row. But the Scottish first minister insisted there was a case for Scotland being able to hold a referendum without asking London first, and hasn't relaxed his view that the vote should be held in the autumn of 2014.

"There's certainly a difference of view. The UK government has come up with one view... there's a great deal of legal opinion that the Scottish parliament can bring forward a consultative referendum," he told Radio 4's Today programme.

However in a political attack on David Cameron, Salmond reiterated his view that the Conservative PM was meddling with Scottish affairs.

"The objection is that the prime minister suddenly this week decided to start pulling strings and setting conditions," he said,

Salmond said he would be prepared to agree the ground rules "sometime this year", but rejected the idea that a third option on the referendum ballot paper - the so-called "Devomax" option of complete monetary independence for Scotland without breaking up the UK - should be ruled out.

"It's wrong at this stage to exclude a legitimate point of view in Scotland that is widely canvassed and supported," he said.

Yesterday the Scottish Secretary Michael Moore outlined his proposal to change the law to allow Scotland to hold a referendum in its own right

The Westminster government's position is that no independence referendum can be triggered by the Scottish Parliament under the current devolution laws. The coalition has now launched a consultation during which the Westminster government expects a deadline to be set for a referendum.

Westminster politicians want the vote to be held before 2014, possibly as soon as in a year's time.

But the SNP appear to be unwilling to negotiate the date, with Scotland's Deputy First Minister announcing last night - on Twitter - that their preferred date for Independence referendum was Autumn 2014.

The coalition government admits it is in untested territory, but believes a referendum could be held as early as a year from now.

Ministers have drawn up what's called a Section 30 Order, which would allow Scotland to hold a referendum without asking Westminster for permission, however this order needs to be agreed by both the parliaments in London and Edinburgh first. However it has attached a rider to the order, suggesting a deadline for the referendum should be agreed before the law is changed.

Sir Menzies Campbell, former Lib Dem leader and Scottish MP, told Today on Radio 4 that the legal row "has potential for very great difficulties all-round.

"No-one is challenging the fact that Mr. Salmond has a political mandate to hold a referendum, he's politically entitled," he said. "But there's an important distinction between a political mandate and legality. Does Scotland remain a member of the European Union if it were to go? These are fundamental questions which need to be resolved.

"Independence is not just for Christmas," he added.

Many political commentators believe Alex Salmond has the political upper hand over David Cameron - even if the law remains on the prime minister's side.

The BBC's political editor Nick Robinson describes Salmond as "the canniest political operator in these Isles", suggesting the Scottish first minister may have known the whole legal wrangle would blow up in the way it has.

Alex Salmond was clear on Tuesday morning that the Westminster government's posturing was encouraging support for independence within Scotland, describing David Cameron's statements on the controversy at the weekend as "Thatcher-esque."

However Nick Watt at the Guardian detects the hand of George Osborne in the coalition government's plan, suggesting that the chancellor is relaxed about pushing the independence issue to the wire. It's widely agreed that if Scotland became independent of Westminster, Labour would be unable to form a government in London for a generation because it would be deprived of its many Scottish seats in the Commons.