SNP chances of forming the next Scottish Executive appear to be receding after a new poll revealed that the party were eight points behind Labour.

The new snapshot of opinion revealed Labour polled 38% on first-vote intentions, a result which would see almost all of their MSPs hold their seats at Holyrood.

It would also deliver a second election victory for First Minister Jack McConnell and put him in a strong negotiating position with the LibDems.

The boost for Scottish Labour, on the eve of their conference this week in Oban, is contained in a leaked TNS System Three poll.

An opinion poll conducted in October 2006, seven months before next May's Holyrood election, confirmed Labour were still Scotland's dominant party on a first-past-the-post basis.

Figures show Labour on 38% of first vote intentions, eight ahead of the SNP, with the LibDems on 14% and the Tories on 12%. The Greens and the SSP were both found to be on 3%.

The findings have pleased Labour strategists because they show the party are currently polling a higher percentage share of the vote than they did at the 2003 Holyrood election, when they were on 35%.

They are also putting a smile on Labour faces as 46 of the party's 50 MSPs are elected by first-past-the-post, almost all of whom would be safe if the poll is translated into seats next year.

In addition, the poll mirrors TNS System Three's September snapshot, which also placed Labour eight points ahead of the Nationalists. But the SNP will take some comfort from the first-vote poll as they are up six points from 2003 and up 2% from last month. However, the poll would see the SNP narrow the gap with their main rivals, rather than close it.

One factor in the SNP's favour is that while the SSP and Greens polled 6% between them, neither is expected to field first-past-the-post candidates next year, leaving a sizeable chunk of votes out in the open.

The snapshot also puts the SNP in first place on the second vote, on 33%, three points ahead of Labour. The LibDems trail on 17%, while the Tories are slumped on 9%. The Greens polled 6%, two in front of the SSP.

The second vote prediction means the SNP are up 6% since September and 12% since May 2003.

However, such a result would mean the Nationalists taking list seats off the Tories and the SSP, rather than Labour, which is up 2% on the second vote compared to last month.

The TSN System Three poll is a counterpoint to other surveys which show the SNP inching ahead of Labour. A Mori poll in June put Labour two points behind the SNP on first-vote intentions, while a Scottish Opinion sample showed the SNP ahead in number of supporters.

Duncan McNeil MSP, who is on Scottish Labour's Holyrood campaign team, said: "This poll is encouraging but we know that poll ratings are not the same as real results. That is why we will be stepping up our campaign over the coming months.

"Come next May the choice voters will face is between investment in schools to make our education system the best in the world or separation and isolation with the nationalists."

An SNP spokesman said: "This poll shows the only party with real momentum, six months before the election, is the SNP. It's now clear the election is a two-horse race between the SNP and Labour."