The Greens are angry about local Lib Dem councils

The Greens - who are staging their own conference a few miles away in Hove - attacked Lib Dem councils' support for new roads and airport expansion.

Sir Menzies Campbell's claim to be the "party of substance" on the environment was a sham, a Green spokesman added.

The Lib Dems launched a series of Green tax proposals this week.

But former Lib Dem activist and Green councillor Rupert Read, who was among those demonstrating outside the Brighton centre, said they did not go far enough.

"It is impossible to have a Green agenda when you are in favour of rampant economic growth and you have a conference sponsored by large corporations," he said.

'Climate crazy'

Mr Read, who is one of nine Green councillors on Norwich City Council, said the Greens' policy of a personal carbon allowance for every citizen would be more effective at cutting emissions than the Lib Dem tax on polluting behaviour.

The protesters, who were chanting "stop Ming's climate crazy councils", said they were angry about Lib Dem support for schemes such as the expansion of Norwich airport.

Jim Killock, a member of the Green Party 's National Executive, said: "Actions speak louder than words. Around the country, Lib Dems are showing where their party's real priorities lie - in supporting building roads, expanding the aviation industry, and failing to recycle.

"The Green Party are the only party that have the political will to really tackle climate change.

"Our record in local government, in Europe, in Scotland and on the London Assembly speaks for itself. "

He said the Greens' annual conference would focus on heath and education issues and how to promote "both social justice and environmental justice".

A Lib Dem spokesman said he had not realised the Greens were holding their autumn conference this week.