John Swinney accused Jack McConnell of letting Scotland down

Mr Swinney accused the first minister of putting his party's interests before the national interests of Scotland.

The latest clash came during an SNP-led debate in the Scottish Parliament.

The Nationalists urged Tony Blair to remove a controversial clause giving Brussels exclusive power over Scottish fisheries.

However, Jack McConnell ruled out any deal with the SNP on Wednesday and accused Mr Swinney of adopting an isolationist stance.

His attack came in response to a public appeal by Mr Swinney last weekend for a deal with the UK Government over the referendum on the constitution promised by Mr Blair.

Mr Swinney told the prime minister that the SNP would only campaign for a "yes" vote in the referendum if the clause on fishing was removed.

There is not going to be any deal with the British Government on this issue Jack McConnell

The SNP leader told BBC Radio Scotland that a spokesman for Foreign Secretary Jack Straw and Labour MPs George Foulkes and Michael Connarty "made it clear" at the weekend that they wanted to talk about a deal with the SNP.

He added: "What has happened in the last 24 hours is Jack McConnell, the first minister of Scotland, as usual, has said he wants nothing to do with it, he wants to put the party political interest of the Labour Party ahead of the national interest of Scotland.

"That's typical of how Jack McConnell goes about his business because he always lets down the national interest of Scotland."

However, Mr McConnell said he had spoken to the foreign secretary and knew there was "not going to be any deal with the British Government on this issue".

Mr McConnell ruled out any deal with the SNP

He said the UK Government wanted to stop Brussels getting new powers and did not regard the inclusion of fishing in the constitution as a new power.

"There is no prospect - absolutely no prospect - of the 25 nations in the new EU agreeing to not have a competence over the marine biological resources," Mr McConnell said.

Tory Europe spokesman Phil Gallie agreed with the SNP that the constitution would "cement the common fisheries policy deeper into the EU web".

But he warned that the constitution would also tighten Brussels' grip over energy and that would have "extremely damaging" consequences for Britain's North Sea oil fields.

'Cruel myth'

Mr Gallie said the constitution would impact on far more than Scotland's fishing rights and went on to list a range of issues including foreign affairs, defence and taxation.

"The issue of the EU constitution, the sovereign rights of all Scots and all citizens of the United Kingdom is far too important an issue to play knock-about policies with," he said.

Closing the debate for the executive, Environment Minister Ross Finnie - making his first speech to Parliament since his return after successful heart surgery - rounded on the Nationalists, whom he accused of perpetuating "a cruel myth" by arguing for exclusive control of fishing.

He said: "To even suggest that Scotland on its own can manage the biological resources in Scotland's best interests - on its own - is a myth."