A former Scottish Secretary has said giving Alex Salmond control over a referendum on Scottish independence is like "putting a fox in charge of the chicken coop".

Lord Forsyth of Drumlean was speaking as peers approved an order to allow the Scottish Parliament to hold a referendum on independence in autumn 2014.

Addressing peers on 16 January 2013, Lord Forsythe warned about a "creeping complacency" in the Unionist campaign that was "very worrying".

He said: "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.

"The Scottish government can't be a participant and a referee at the same time."

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.

"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."

Liberal Democrat Lord Stephen said the question suggested by Mr Salmond - "Do you agree that Scotland should be an independent country?" - was "rigged" on "at least two grounds".

Advocate general for Scotland, Lord Wallace of Tankerness, told peers the referendum would 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.

The order, which was approved by MPs earlier in the week, was passed by peers without the need for a vote.

Speaking in the earlier Commons debate, the SNP's leader in Westminster, Angus Robertson, said devolving the power for the referendum was a "huge milestone".

He told MPs: "It says much about the potential for further respect and equality between the governments, the parliaments and the peoples of these islands."