ITV's head-to-head between Prime Minister Boris Johnson and opposition Labour leader Jeremy Corbyn is slated to take place on Tuesday, the BBC reported.
When ITV announced its plans, the channel said it would hold a live interview-based programme alongside the leaders' head-to-head to allow other parties to comment, as well as another multi-party debate ahead of the December 12 general election.
The two parties have said that it was unfair not to invite them to take part.
The SNP said it expected the High Court to decide on Monday whether the two legal challenges should be heard together and a ruling was expected later in the day.
Speaking ahead of the hearing, SNP Westminster leader Ian Blackford, told the BBC: "This challenge is not just about the SNP, it's about fairness for every voter and viewer across the country who have a right to see the real choice at this election on that debate stage.
"By excluding key parties from the debate, viewers are being deprived of the opportunity to make their own decisions, and voters in Scotland are not seeing their voting patterns reflected at all.
Meanwhile, the Liberal Democrats said that it was wrong to exclude "a voice of Remain" and the only female candidate party leader Jo Swinson for Prime Minister from the head-to-head debates.
It has also sent a legal letter to the BBC over its decision not to include their leader Jo Swinson in a debate on December 6.
( With inputs from IANS )