A Green city councillor has resigned little more than five months since he was elected – blaming the party's 'profoundly undemocratic' methods.

David Rogers informed Norwich City Council of his decision yesterday, after expressing his dissatisfaction with how the Norwich branch of the party is run.

Nelson ward member Mr Rogers said the party attracted the 'gullible and the authoritarian', which he said was a 'dangerous combination in party politics'.

Mr Rogers said: 'I agree with the Green Party aims to create a fair society and to deal with the threat from rapid climate change.

'However, I cannot accept its methods; it is profoundly undemocratic.

'Norwich Green Party has an executive of elected members who should execute decisions made by the party membership. The membership rarely makes a decision and when it does it is usually ignored.

'It is possible that the national Green Party is not aware of this. If it isn't, it should be. Norwich Green Party is the second largest in the country and has the largest number of councillors.'

Mr Rogers, a Green Party campaigner since 2005, was elected in May. He received 1,644 votes – a 59.5pc share of the 2,763 votes cast at the ballot box.

His announcement means the Greens now have 14 seats, Labour 21 and the Liberal Democrats three.

Mr Rogers said he had no intention to become an independent or switch to another party.

He added: 'I can no longer support the Green Party. I have seen the dangers that the Green Party presents and I must oppose the Green Party.'

Claire Stephenson, Green Party group leader at the city council, declined to comment on Mr Roger's claims about how the Norwich Green Party's executive operates.

But she said she was 'sad' that Mr Rogers had decided to resign as she believed he had plenty to offer.

She said: 'Councillors are there to represent their residents and David has been an enthusiastic councillor, has done a good job for residents so far and it's a shame that he will not continue.'

A by-election, estimated to cost taxpayers �10,000, is expected to be held to replace Mr Rogers. No date has been set.

A city council spokesman said: 'If a councillor wants to resign, they must notify, in writing, the proper officer – in this case Philip Hyde, the council's head of law and governance.

'When a by-election has been called, polling day must be within 35 working days. The anticipated cost of a by-election is around �10,000.'