Greens challenge TV broadcast omission
The Green Party says it will challenge the BBC's decision not to offer it a party political broadcast - while UKIP is to be allocated three annual slots.
It has launched a petition against what it calls a "broadcast blackout", saying it increased its vote share and has the same number of MPs - one - as UKIP.
The BBC based its decision on new rules for how broadcasts should be allocated.
The BBC Trust guidelines highlight an "unexpected discrepancy" between the number of UKIP MPs and its vote share.
Party political broadcasts take place three times a year in England, Scotland and Wales and once a year in Northern Ireland.
The latest allocations were announced on Monday, with UKIP joining the Conservatives, Labour and Lib Dems in the list of parties being offered broadcasts in England.
Green Party leader Natalie Bennett said she was "astonished" her party was being denied "vital broadcast coverage".
"We've grown as a party by more than three times in the last 12 months," she said.
"I'm starting to wonder what exactly it is that we need to do to convince the BBC to grant us fair representation."
The party said it would request an urgent meeting with the BBC and urged support for a petition on the 38 Degrees website.
The BBC Trust, which carried out a public consultation on the new criteria for inclusion, said the previous guidelines, set in 2012, "did not anticipate the anomaly arising from an unprecedented discrepancy between representation (seats) and share of the vote in the last general election".
It said this was particularly the case with UKIP, which could have missed out despite having a larger vote share at the general election than the Lib Dems.
In light of the promised in-out EU referendum, it added: "The BBC Executive considers that it could be an exacerbating factor if a party which was unambiguously in favour of leaving the EU was unfairly denied" party political broadcasts.
In Wales, Plaid Cymru is also included, and in Scotland the list is made up of the SNP, Labour, the Tories and Lib Dems.
In Northern Ireland broadcasts have been offered to the Democratic Unionist Party, Sinn Fein, the Ulster Unionist Party, the SDLP and the Alliance Party.