A new briefing from the Green Party, published today, argues that UKIP is a party of backward-looking policies, a party of "climate change denial" - and a party with a fundamental flaw at the heart of its anti-EU policy.
"The core of UKIP's platform in this election is the illusion that if we left the EU we would not have to follow its rules," says the briefing. "The reality is that we would still need to follow EU regulations in order to be able to trade with Europe, but we would have no say in drawing them up."
It continues: "The whole machinery of governing the environment, industry and trade is so closely bound up with the EU that withdrawal would bring disruption which would do the UK economy no good at all in the current recession...
"UKIP's vision harks back to a previous world and refuses to acknowledge the urgent problems of the present. UKIP oppose, for instance, the banning of harmful pesticides and weed-killers. They favour policies such as the expanded building of coal-fired power stations and they oppose green taxes and windfarms.
"While UKIP offers all these backward-looking ideas, the Green Party offers a forward-looking vision for a better future for Britain and for Europe. This would involve remaining within the EU to work with it on the major changes in economic strategy that the present economic crisis and the on-going climate change crisis demand."
The briefing, Thinking of voting for UKIP? Think Again can be found here: