The Lib Dems have asked Ofcom to investigate alleged bias in GB News' coverage of the Post Office scandal, including attacks on Sir Ed Davey.
The party claims GB News hosts Nigel Farage and Sir Jacob Rees-Mogg targeted opposition politicians but overlooked Tory MPs' role in the scandal.
Sir Ed, the Lib Dem leader, has been criticised for his initial refusal to meet campaigners while minister responsible for the Post Office.
GB News has been contacted for comment.
Separately, Labour have accused the Conservatives of trying to "sling mud" at opposition politicians over the Post Office IT scandal.
While the vast majority of prosecutions of sub-postmasters were private prosecutions pursued by the Post Office, it emerged on Wednesday that three were prosecuted by the Crown Prosecution Service while Sir Keir Starmer was director of public prosecutions.
Wes Streeting, the shadow health secretary, told OceanNewsUK: "I think what's actually happened in the last week or two in particular is the government have tried to sling mud at everybody else.
"They're trying it with Keir Starmer, they've tried it with Ed Davey, and I think it's unedifying actually."
Mr Streeting said "ultimate responsibility" for the scandal lies with the Post Office, and Fujitsu - who made the faulty Horizon software that made it look like money was missing.
'Democracy deserves better'
Daisy Cooper, the Lib Dem deputy leader, wrote to Ofcom claiming Mr Farage launched "a fictitious monologue" about Sir Ed which contained "a number of factual inaccuracies" in his show on Tuesday.
"The Liberal Democrats were offered no right of reply. This therefore breaches both the accuracy and impartiality elements of the Ofcom code," Ms Cooper said.
Sir Ed has faced some criticism for initially refusing to meet Alan Bates, the post office operator who led the campaign against the injustice. He subsequently became the first minister to then meet Mr Bates.
Mr Farage, the honorary president of Reform UK, the new name for the Brexit Party, hosts a daily evening news show on GB News, which airs before former Tory cabinet minister Sir Jacob Rees-Mogg's programme.
Ms Cooper accused Sir Jacob, of taking aim at "political leaders from other parties about the scandal, whilst not mentioning his own party's role in this devastating miscarriage of justice".
She said there was no mention that the Conservatives oversaw ex-post office chief Paula Vennells receiving a CBE and "then made her a non-executive board member in the government".
"Nor did he mention that the governments of which he was a part dragged their feet over financial redress for the victims," she wrote.
Ms Cooper said she had no confidence that Lee Anderson, the Tory deputy chair, would be impartial during his GB News show on Friday. Mr Anderson used a question in the Commons to call for Sir Ed to quit on Wednesday.
"This is a general election year. British democracy deserves better than bias, misleading and at times, frankly absurd news reporting of important matters," she added.
GB News has faced a series of Ofcom investigations into alleged breaches of the code - often stemming from shows hosted by politicians.
In September, Ofcom found an interview by Tory MPs Philip Davies and Esther McVey with the chancellor ahead of the Spring Budget breached impartiality rules.
A month later, Ofcom ruled GB News breached impartiality rules in an interview with Reform Party leader Richard Tice by former Brexit Party MEP Martin Daubney.
