Giving Alex Salmond control over a referendum on Scottish independence is like putting a fox in charge of the chicken coop, a former secretary of state said today.
Lord Forsyth of Drumlean also warned about a "creeping complacency" in the Unionist campaign that was "very worrying".
His comments came as the House of Lords debated a Government order that hands power to Holyrood to hold the poll in the autumn of next year.
Ministers say the legal order, which was approved by MPs yesterday, would give the Scottish Parliament the legal, fair and decisive referendum pledged in the Edinburgh Agreement and signed by Prime Minster David Cameron and First Minister Alex Salmond last year.
But Tory peer Lord Forsyth, who was Scottish secretary from 1995-97, hit out at the "trust" being put in Mr Salmond.
"It is a bit like putting a fox in charge of the chicken coop and arguing the chickens will protest if it all goes wrong," he said.
"The Scottish Government can't be a participant and a referee at the same time."
He said power was being given to the Scottish Parliament "but in fact the Scottish Parliament is one man - it is Alex Salmond".
"He completely dominates the Scottish Parliament," Lord Forsyth said. "We are passing responsibility for the conduct of the referendum to a man who has made it his life's work to destroy the United Kingdom,
"We are doing so without knowing the question, without knowing the date of the referendum, without knowing the rules on expenses for the conduct of the referendum and without even knowing who is going to be allowed to vote in the referendum - and that is after seven months of negotiation between the Government and the First Minister."
He warned that although support for the referendum campaign was only at 33%, there had been a similar level of support for Quebec secession at the beginning of a referendum campaign and yet the argument had been won by only 0.6%.
"So let's not be cavalier in giving away things that would make all the difference," he added.
Lord Forsyth also hit out at the "casual way" in which the Government was happy to let the franchise for the election be extended to 16 and 17 year olds.
"What we are suggesting here is that people in Scotland should not be able to buy a packet of fags, or a packet of sparklers or a drink in the pub, but they can decide the future of the United Kingdom and that all of this can be done on the basis of what Alex Salmond decides when he gets out of bed in the morning is I think utterly frightening and if ever there was a case of the tail wagging the dog this is it," he said.
Labour former Cabinet minister Lord Reid of Cardowan said the Government had been "weak" on the question of timing and said it was not in the interests of Scotland to delay the election until next year.
But he said: "I'm not frightened of Alex Salmond and I don't know why we give him the status that appeared to be given earlier on (by Lord Forsyth).
"I believe we should have a confidence that ultimately this decision will be made by the Scottish people. We may have a fox in charge, but we don't have chickens.
"We have five and a half million or thereabouts of good strong people in Scotland who will make their own decisions after an aggressive argument.
"But on the timing I think the Government were weak. If they had truly been speaking for the people of Scotland they would have said 'let's have the decision now, we've been debating this for decades'."
Advocate general for Scotland Lord Wallace of Tankerness, introducing the order to the Lords, told peers: "Scotland's future within this United Kingdom will be the most important decision which we in Scotland take in our lifetime.
"Facilitating a legal, fair and decisive referendum is critical. That is why we consulted on the issue, that is why both the Scottish Government and the United Kingdom Government spent many hours discussing the process."
He said passing the motion would allow a move from a debate on the process to a debate on the substance of the issue.
"It is essential that the referendum decision is focused on determining whether Scotland chooses to remain an integral part of the most successful partnership of nations this world has ever seen and remain a part of a family of nations that works in the interests of all or whether it chooses to separate and go it alone," he said.