Plans to give Holyrood temporary powers for a legally binding referendum on Scottish independence will be set out by the government on Tuesday as tensions between Westminster and Scotland intensify.

Scottish Secretary Michael Moore will tell MPs the coalition wants the vote to be held "sooner, rather than later" but he will not set a previously expected deadline of 18 months on the vote, government sources have said.

The news follows warnings by prime minister David Cameron and chancellor George Osborne about the effect of uncertainty about Scotland's future on the UK's economy.

The government's intervention was greeted with anger by the Scottish National Party administration in Edinburgh, which accused London of trying to interfere in a matter which should be settled north of the border.

Cameron denied trying to "dictate" the terms of the referendum from Westminster, and insisted it will be for people in Scotland to decide whether they stay in the Union.

"We have to have legal clarity over who is responsible for this decision. Is it the Westminster Parliament or is it the Scottish Parliament? We will be setting out the legal position and trying to find a way through," he told Sky News.

Advice received by ministers on the legal implications of a referendum will be published alongside the government's proposals in the next few days.

Salmond's deputy Nicola Sturgeon denounced the move as "a blatant attempt to interfere in the decision that is really one for the Scottish Government in terms of the timing of the referendum and for the Scottish people in terms of the outcome".
She added: "We were elected on the basis of our commitment to have a referendum in the second half of this parliamentary term. This is about Westminster seeking to interfere."

Sturgeon indicated that the referendum would include three questions, yes to independence, no to independence and a third option labelled 'devo-max', more devolution without Scotland leaving the United Kingdom.

Speaking on Tuesday morning, chief secretary to the Treasury Danny Alexander said that "jobs, investment and growth" were much more important priorities for holding a referendum then when the SNP proposes to hold the ballot.

"We want to be reasonable about it rather than waiting for them to come forward with a plan and then entering into years of legal wrangling of the sort that happens in other countries where they have separatist movements trying to break up their country," he told Radio 4's Today programme.

A spokesman for Salmond said that any attempt by Westminster politicians to dictate the terms or format of the referendum would only fuel demands for independence.

"The days of Westminster determining what happens in Scotland are over. We'll bring forward our proposals, we'll stick to what we said we would do in the election."