The Greens are considering legal action against the BBC because TUV had a relatively longer run during the assembly’s election campaign, even though it had less MLA.
The party lodged formal complaints with the BBC and broadcast regulator Ofcom and launched an online petition.
TUV leader Jim Alistair was the party’s only MLA prior to the dissolution of Stormont ahead of the May elections.
The Greens had two MPs: party leader Claire Bailey in South Belfast and North Down Rachel Woods.
However, TUV scored a slightly higher lead in the 2017 assembly elections with 2.6% compared to 2.3% for the Greens.
Some opinion polls in recent months indicate an increase in support for TUV due to the split in the union vote.
Bailey accused the BBC of choosing “divisive and agitated” over the Greens’ “real alternative to traditional partisan politics”.
He said, “Our public broadcaster has a duty to take sides, especially during the election campaign.
“However, the BBC has decided to cover a larger number of TUVs smaller than the NI Greens, including additional election coverage.
“In the last election, the Green Party, NI, won more seats in the assembly and city council than the TUV, so it makes no sense for the BBC to consider the TUV to be bigger than the Greens.
The main opposition party in any other democracy will not be excluded from the electoral debate and from coverage of other elections.
We have submitted formal complaints to the BBC and Ofcom and the NI Green Party is actively evaluating its legal options.
Ms Bailey called on the public to sign the petition on the party’s website to show that they are “against the distortion of our democracy”.
A BBC spokesperson said: “We have a rigorous and detailed process on how to decide on party coverage during the election period.
“This takes into account relevant Ofcom requirements and BBC Election Guidelines.”
A TUV spokesperson also said the coverage given to the party did not reflect “our level of support”.
“The lively TV media coverage of TV media is dictated by political documents prepared by broadcasters long before the elections,” he said.
The increase in TUV support, which was reflected both in the sharp increase in the number of subscribers and in numerous opinion polls, is a matter of public knowledge.
“This is because people understand and appreciate TUV’s position on the Northern Ireland Protocol.
TUV says broadcasters’ coverage of the campaign does not really reflect our level of support.
“Recent opinion polls showed the support for TUV above that the coalition showed before the last election, however they were in the leaders’ main debate and TUV will be disqualified.”