BBC Scotland chiefs have been accused of being “disconnected from reality” after proposing to give Ukip as much coverage as the Scottish Greens at the Holyrood election.

Despite the Greens having two MSPs and polls suggesting they could get nine in May, the BBC Trust has proposed treating them as a “smaller party”, meaning very limited airtime.

That puts them in the same category as Ukip, who have never had an MSP, and who got less than 1 per cent of the vote at the 2011 Holyrood election.

However the LibDems, who face a potential wipeout, are still classed as a “larger party” under the BBC plans, meaning “broadly similar” coverage to the SNP, Labour and Tories.

The Greens have now launched an online petition to demand the same coverage as the other Holyrood parties.

One Green source said: “It's like the BBC Trust has drawn up this guidance in a bubble. Disconnected from the reality of Scottish politics.”

The BBC Trust issued draft editorial guidelines on impartiality for the Scottish elections in November, and an eight-week consultation on them closes on January 15 .

The starting point for allocating airtime is each party’s performance at the last Holyrood election, but later elections and robust polling trends can also be factored in.

A BBC background document describes the LibDems as the “biggest losers” of 2011, down from 16 MSPs to five, with vote share halved in both constituencies and regional lists.

The document notes the LibDem list vote, of 5.2 per cent, was “less than 1 per cent ahead of the Scottish Green party, who again won two seats” with an improved 4.4 per cent vote share.

“Ukip took less than 1 per cent of the regional vote,” it notes.

Although Ukip won its first Scottish MEP in 2014, at last year’s general election it averaged fewer votes per seat than the Scottish Greens.

However the draft guidelines state: “Since 2011, Ukip has demonstrated an increase in support in Scotland and this should be reflected with coverage up to a similar level to the Scottish Green Party.”

Patrick Harvie MSP, the Green Party's co-convener, and his advisers recently met BBC political adviser Ric Bailey, BBC Scotland acting head of news Pete Macrae and incoming head of news Gary Smith to complain.

They pointed out the Greens averaged 8 per cent in 2015 polls - more than the LibDems had averaged in two years - indicating a record number of Greens MSPs in May.

Harvie was also rated the most popular leader at Holyrood after Nicola Sturgeon, and the Scottish Greens had over 9000 members, more than three times the LibDems.

Lothians Green MSP Alison Johnstone said: “Only five parties have won continuous representation in the Scottish Parliament and the Greens are one of them.

“It is disappointing that the BBC Trust's proposed guidance does not reflect this.

"Polling clearly shows the Greens on course to outnumber the Lib Dems, so the proposal to give them parity with the other three parties but relegate us does not add up.

“Given the significant role Scottish Greens are likely to play in the next parliament, the public deserve to hear and scrutinise what we have to say.

“We'd urge anyone who believes the Scottish Greens deserve fair treatment from the BBC in the run up to and during the 2016 election to join us in making this case."

A BBC spokesperson said: “The Trust is holding a public consultation on the Election Guidelines and the Scottish Green Party, along with all other political parties, have been invited to make submissions – the Trust will make a final decision in February.”