Labour leader Ed Miliband has launched a scathing attack on the government’s handling of energy policy, revealing new figures that suggest investment in UK renewable energy has fallen by half since 2009.

In a speech at Whitelee Wind Farm in Scotland, Miliband criticised the apparently increasingly anti-green rhetoric emerging from Westminster, particularly single out Energy Minister John Hayes and Chancellor George Osborne. He said: “David Cameron promised that this government would be the greenest government ever. But this government is not up to the task. We now have a Minister for Energy who is against building new wind turbines – and a government that has delayed crucial decisions on the Green Investment Bank and de-carbonisation targets.

“George Osborne is trying to undermine the Climate Change Act, leading the dash for gas and pandering to the climate sceptics on the back benches. We even had the spectacle of the campaign manager for one of their by-elections conspiring with the anti-wind farm candidate, and undermining their own candidate.

“Already billions of pounds in investment is going elsewhere or being put on hold. Thanks to this government, the investors who want to invest in our green sector are shutting their wallets or going elsewhere. Since this government came to power, investment in renewable energy hasn’t gone up, it hasn’t even stagnated – it has halved.”

New analysis from Bloomberg New Energy Finance cited by Labour suggests investment in renewable energy in the UK has fallen from US$10.65 billion in 2009 to US$5.04 billion last year.

Miliband’s attack follows new rumours that the delayed Energy Bill will now not include a grid decarbonisation target, although the Energy Secretary Ed Davey has made it clear that he is in strong personal favour of its introduction.

Miliband called on government to commit in the Energy Bill to a 2030 decarbonsiation target. He said: “That is what I would do if I was in Downing Street now and that is what this Prime Minister – who once flew halfway across Europe to hug a huskie – should do.”

The much-anticipated Energy Bill is expected to be announced early next week. Miliband had previously called on governments around the world to commit to a carbon-free power sector by 2030, stressing the importance of the green economy in helping lift countries out of the current economic mire.

Referring to the Bloomberg figures, Martin Wright, chairman of the Renewable Energy Association, said: “These figures illustrate that capital is voting with its feet. The last few years has seen renewables emerge as a serious contender. Costs are falling, supply chains are gearing up and renewable energy is no longer a cottage industry.

“The UK must capitalise on this, and can’t afford to lose momentum. It is essential that swift, clear decisions are implemented by a Government united in the objective of keeping the lights on whilst sticking to its climate change objectives. That’s what it said it would do and what the Energy Bill must deliver.”