Both party leaders supported the work of the Calman commission
Conservative and Lib Dem leaders in Scotland have spoken of their serious concern over Wendy Alexander's policy shift on a referendum on independence.
They said the Scottish Labour leader's new-found support for a referendum was undermining the Calman Commission.
It was set up by Labour, the Lib Dems and the Tories to review the powers of the Scottish Parliament.
Annabel Goldie said she was "totally behind" its work while Nicol Stephen said it was "more important than ever".
Speaking on BBC Radio Scotland, Mr Stephen argued that the Calman Commission should be supported to examine the parliament's powers.
The Liberal Democrat leader added: "Unless the work is done to develop that through the commission then you end up with a very polarised debate between Gordon Brown and Wendy Alexander on the one hand and Alex Salmond on the other.
"Given the popularity of Gordon Brown and Labour Party at the moment I worry about that."
Ms Goldie, the leader of the Scottish Tories, said she had "confidence" in the Scottish people wanting to continue with "improved devolution".
She added: "It really is extraordinary that Wendy Alexander has jumped the gun in a sense by, I think, undermining the status of the commission.
"The outcome of that commission is very, very important to the informed debate that many people in Scotland want us to have."
Mr Stephen also spoke of this week's events being "absolutely extraordinary".
They were speaking after Ms Alexander called for an early referendum on independence, challenging the SNP to "bring it on".
The SNP leader at Westminster, Angus Robertson, also joined in the criticism, pointing out that Scottish Secretary Des Browne had rejected a referendum as recently as April.
It is extraordinary that the voice of the Secretary of State has not been heard
Shadow Scottish Secretary
"Amidst all the U-turns and erratic behaviour there is an eerie silence from the Scotland Office," said Mr Robertson.
"Des Browne has been adamant in his opposition to a referendum. What does he think now?
"Does he agree with Wendy Alexander or is he behind Gordon Brown's decision not to back her latest 'big idea' - which is of course the SNP's idea?"
The Shadow Scottish Secretary David Mundell has also written to Mr Browne questioning his absence from the debate.
Mr Mundell said: "It is extraordinary that the voice of the Secretary of State has not been heard."
Mr Mundell's letter follows an exchange of letters between the UK Tory leader David Cameron and the Prime Minister in which he has sought clarification over the Labour Party's position.
In a statement, a Scotland Office spokesman said: "The Scotland Office's position is that of the [UK] government, which the PM set out earlier this week: The Commission on Scottish Devolution, the Calman Commission, has been established to look at ways in which the current devolution settlement might be strengthened to better serve the people of Scotland and to continue to secure the position of Scotland within the UK.
"We will look at the findings of the commission and decide how to move forward in light of them. The Secretary of State backs the commission and indeed was involved in its establishment."
The 15-member commission, chaired by Sir Kenneth Calman, only met for the first time at the end of April.
It is not expected to report until later in the year.
John Loughton, a member of the Commission, said he had been surprised at Ms Alexander's change of stance.
"What I want to hear from the opposition party, what is the fundamental duty of an opposition party, is to propose a clear, consistent and key message in providing solutions or alternatives to proposals from government," he told BBC Radio's Good Morning Scotland programme.
"Sadly I think that's not happened through various changes in stance from the Labour party just now."