One of Britain’s biggest employers in the green energy industry is to cease production within hours of a government announcement today pledging as many as 400,000 green jobs by 2015.

Ed Miliband, the Energy and Climate Change Secretary, will claim that Britain will become a world leader in low-carbon technology and manufacturing. He will argue that raising household energy bills to pay for investment in wind, solar and tidal power is justified not only by the dangers of global warming but also the opportunity to build a new “green economy”.

However, tomorrow morning the Vestas factory in Newport, Isle of Wight, Britain’s only significant manufacturer of wind turbines, will produce its last batch of seven-tonne blades. More than 600 people employed at the plant, and a related facility in Southampton, will be made redundant at the end of the month. All 7,000 turbines that the Government will commit today to installing over the next decade will be manufactured overseas, mainly in Germany, Denmark and China.

Vestas managers and union leaders held meetings with Mr Miliband and officials to discuss the possibility of converting the factory — which supplies the US market — to produce a different type of blade suitable for British wind farms. The Government did not, however, offer any financial aid and was unable to give any assurances that it would break the planning logjam that has paralysed the British market for wind turbines.

In April, the Scottish government gave £10 million in grants to save 100 jobs and possibly create 200 more at a much smaller turbine factory in Argyll.

Wind power will be at the centre of today’s Renewable Energy Strategy and Low Carbon White Paper, which will set out how each sector of the economy will help to meet the overall target of a 34 per cent cut in CO2 emissions by 2020.

Mr Miliband will say that more than £100 billion will be invested in raising the proportion of energy from renewable sources from 2 per cent at present to 15 per cent by 2020.

Workers at the Vestas plant, however, questioned whether the Government’s pledges could be taken seriously when ministers had done nothing to save their jobs. Peter Hunt, a safety administrator at the factory, said: “If the Government was as committed to wind power as it claims, why is it acting so slowly to improve the planning process? We need a central planning body to overcome the not-in-my-back-yard groups who are blocking British wind farms. But if it comes, it will be too late for us.”

Local groups opposing wind farms on the ground of visual intrusion have blocked almost half of the 93 applications made in the past three years and delayed the remainder for as long as two years. Several sites have been identified on the Isle of Wight but it has no turbines, partly because of a hate-mail campaign targeting landowners involved in applications.

Reg Barry, a Liberal Democrat councillor, said: “Why are we subsidising foreign car factories with the scrappage scheme but doing nothing to protect jobs in our greenest industry? The factory closure will be devastating for the island. These are 600 well-paid jobs on which you could raise a family and pay a mortgage, not temporary tourism jobs.”

A spokesman for the Department of Energy and Climate Change said: “Ultimately it was a commercial decision for Vestas. But the Renewable Energy Strategy is going to be a massive opportunity for manufacturers generally.”

Jack Dromey, deputy general-secretary of the union Unite, said: “It would be a bitter irony if there was a boom in British wind farms but the wind turbines were made on the Continent and in China.”

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