Colin Blane: Mr McLetchlie says he wants to defend the Union

David McLetchie - speaking to the Scotland on Sunday newspaper - said his party would back a minority Labour administration if it was facing a vote-of-no-confidence.

Anti-nationalist alliance

His remarks are being hailed by some commentators as the first step towards the formation of an informal unionist coalition designed to stop the Scottish National Party seizing power.

John Pienaar: Mr McLetchie wants to unite against the "wreckers" of the new Parliament

The move is also being interpreted as an attempt to reduce the Liberal Democrats' bargaining power in any round of post-election negotiations if no single party enjoys a majority.

Mr McLetchie said: "If you (Labour) are the biggest party then there is no need to go into partnership with the Liberal Democrats.

"At the end of the day we are not in the business of bringing anybody down or disrupting the government of Scotland.

"As a point of principle we would not vote with the Nationalists to bring down an administration. We have no wish to bring problems or confusion to the Scottish Parliament.

"We would never do anything which would help the separatists."

'Not terribly helpful'

Some delegates attending the Scottish Conservative Conference in Perth, have criticised Mr McLetchie, saying his tactics are premature ahead of the elections to the Parliament.

It is possible no party will have an overall majority in the Parliament

Struan Stephenson, a prospective Tory candidate, said: " If you are a poker player you don't really expose your hand before the game.

"I think these matters are better left until after 6 May until we see how the votes shake out - will there be coalitions, who will be in the coalitions. And I think that this sort of discussion right now is not terribly helpful."

However, the Chairman of the Scottish Tories, Raymond Robertson said Mr McLetchie, was merely stating that the party would "never play into the SNP's hands".

He added: "They are wanting the Parliament to fail. They want constitutional instability. We will not play that game."

No outright winner

Mr Robertson also backed Mr McLetchie's claim that the Parliament would be very different from Westminster politics.

He said that as the elections would take place under a system of proportional representation it was "inconceivable that any one party will have an overall majority".

As a result it would be necessary for parties to work in partnership to pass individual pieces of legislation, Mr Robertson said.