The broadcaster is proposing to have a three-way debate between Prime Minister Boris Johnson, Jeremy Corbyn of Labour and Liberal Democrat leader Jo Swinson on November 28.But Ms Sturgeon accused the broadcasters of "going backwards" after it emerged she would be frozen out. Ms Swinson has already raised the prospect of legal action after being frozen out of the planned November 19 head to head on ITV between the Prime Minister and Mr Corbyn on the channel.
And today the SNP issued a similar warning to Sky News chief John Ryley - making clear the party could test the matter in the courts after Ms Sturgeon was excluded.
"We will consider all of our options," the First Minister said on the campaign trail today in Dalkeith, Midlothian.
"We've written to Sky in the first instance and I hope they take that seriously and I hope they engage with us in this discussion.
"It remains to be seen whether this Sky debate goes ahead because to the best of my knowledge Johnson and Corbyn haven't agreed to it yet."But there's an issue of real principle here of how how can you include the fourth biggest party in the UK in a debate like this and not the third biggest party."We'll take forward these discussions, but I'm ruling nothing out at this stage."
ITN is proposing two debates. One would involved just the two main leaders - Mr Johnson and Mr Corbyn - along with a second debate involving all seven leaders."I think ITN and, we'll see where the BBC get to but I suspect they're going in roughly the same direction, I think they're retreating back the way. If you think about 2010, 2015, 2017, they seem to be making progress reflecting the multi-party, multi-national elections that we have in the UK."This is going back the way at a time ironically when the population appears to be moving away from the rigid two-party system. So they're not reflecting the choice people have as it is."They seem to be trying to reflect it as they want it to be.
"These are big issues and we will continue to have fairly rigorous discussions with the broadcasters, both about leaders debates, but also generally just about how the SNP is reflected in the overall coverage. We could hold the balance of power after this election."She added: "There is a real issue of democracy here - we will continue to progress and see where we get to."The letter from SNP Business manager Kirsten Oswald states points to sections 5 and 6 of the Ofcom code which says broadcasters must ensure that “an appropriately wide range of significant views must be included and given due weight in each programme”. It adds that candidates with significant views and perspectives should be included and you must take into account evidence of past electoral support and/or current support.The letter states: "On an impartial assessment of all of these grounds the SNP is unquestionably entitled to be in any debate in which you intend to include a party which has - and which current polls suggest will continue to have - fewer seats than the SNP and whose view on critical issues in this campaign, such as the future of the UK is no different to that represented by the other two parties."It adds: "If this fundamental issue of democracy is not resolved to our satisfaction, we reserve the right to test the matter in the courts."