ALEX Salmond has delivered his most bullish demand yet for a head-to-head independence debate with David Cameron after they were named joint winners of a prestigious political award.

The First Minister is desperate to do battle with the UK's Prime Minister in the run-up to the referendum on September 18 next year. So far the Tory PM has dismissed all requests, largely leaving any major debate up to Alistair Darling, the leader of the pro-Union Better Together campaign.

But after the Political Studies Association named Mr Salmond and Mr Cameron as joint winners of their Democratic Innovation Award for their work for making the referendum happen via the Edinburgh Agreement, the SNP leader immediately re-issued his call for a head-to-head debate.

He said: "It would seem to me to make it incumbent on the other joint recipient of this incredible award to debate with me as part of the process. We can hardly accept a joint award for political engagement if we are not prepared to follow it through and conduct a debate in democratic terms as the two signatories of this agreement. According to the serious academics this is the best thing since sliced bread."

The tactics of head-to-head debates is a major issue in the referendum campaign. Better Together has left the major debates to Mr Darling, in the belief he would fare better arguing its case in a relatively pro-Labour country, rather than an English Tory.

At the same time, Mr Salmond has been determined to pursue his argument against Mr Cameron, saying the logic of a Prime Minister versus First Minister debate is central to the independence discourse. Hence, he has stayed out of the fray so far until he can lock horns with someone he considers his political equal.

The Political Studies Association, which was founded in 1950 and which publishes research in all areas of politics and international relations, said its panel of experts was unanimous in making the joint award for 2013 following the intense negotiations which brought about the legally binding referendum document.

The jurors agreed the joint decision to hold a referendum on Scottish independence was an act of democratic innovation that should be "acknowledged and celebrated".

A spokesman for the First Minister said: "We are delighted that the Edinburgh Agreement has been honoured in this way.

"The fact that such a distinguished body has chosen to recognise the importance of the accord is hugely significant.

"Of course, as the joint signatories to the Edinburgh Agreement, the First Minister and Prime Minister are the respective leaders of the Yes and No campaigns.

"The Prime Minister deserves credit for his role in securing the Edinburgh Agreement. But this award confirms his central role in the process, and as such it is becoming harder and harder for him to avoid a head-to-head debate on the question of Scotland's future."

So far Ms Sturgeon has taken part in two debates live on television, the first against the LibDems' Michael Moore and the second time she came face-to-face with deputy Scottish Labour leader Anas Sarwar.

The PSA award is due to be presented at an awards dinner in Westminster on November 26 with both the FM and PM invited to attend.