A draft report from the Scottish Affairs Select Committee challenges the claim by the government that a Scottish Parliament would strengthen the UK.

Instead, the 30-page document warns serious conflict is inevitable between Holyrood and Westminster and expresses doubts the Scottish Parliament will satisfy Scots' demands.

'Clash with English doctrine'

The committee, seven of whose 11 members are Labour, also list the areas most likely to cause conflict between London and Edinburgh - including the limited powers of the Holyrood Parliament, the reliance in Westminster for funding and a rise in English nationalism.

The leaked document states: "It is permissible to ask if it would matter, otherwise than sentimentally to some, if the UK were to break up."

The report in The Herald newspaper also criticises the Scotland Act as "piecemeal".

The committee asserts the belief a Scottish Parliament could stage its own referendum in independence.

The report was leaked to The Herald

The report says: "If the Scottish people expressed a desire for independence, the stage would be set for a direct clash with what is the English doctrine of the sovereignty of parliament and the Scottish doctrine of the sovereignty of the people."

The report, to be published on Wednesday, follows several weeks of concerted attacks on the "separatist" Scottish National Party by the prime minister, Chancellor Gordon Brown, Foreign Secretary Robin Cook and most recently Trade Secretary Peter Mandelson.

Scottish Secretary Donald Dewar refused to comment on the leaked report.

He said: "I have spoken to several members of the committee, who do not recognise the report from the reports in the media.

"When the report is published on Wednesday, we expect we will find there has been some selective quoting to make a headline."

'Positive approach'

The SNP's constitutional affairs spokesman George Reid said: "This report simply confirms what the SNP have always said - that Scotland is in a process of independence, with our destination being the normal status of equality in Europe."

Mr Reid continued: "What is important is that the SNP and the vast majority of Scots are approaching the process of independence is a positive manner.

"What will be interesting is the extent to which the New Labour control freaks at Westminster try to re-write the contents of this report - although that won't make the slightest difference to the process of change that is happening in Scotland."