A new generation of nuclear power stations will offer "breathtaking" economic opportunities for British business on a scale not seen since North Sea oil was discovered, John Hutton will say in a speech today.

The business secretary will underline the government's determination to oversee a "significant expansion of nuclear in the UK in the coming decades" rather than simply replacing the existing, ageing fleet of reactors. "I don't want to see just a like for like replacement of nuclear capacity in the UK."

In a speech that will dismay anti-nuclear protesters, Mr Hutton will emphasise the government's aim of ex-ploiting interest from energy companies that "see new build in the UK as a gate-way to the rest of Europe".

A new fleet of reactors "could potentially create up to 100,000 jobs". He will argue that simply replacing the existing fleet of reactors would equate to three times the size of the project to build Heathrow's new Terminal 5. "The potential scale and complexity of each investment is breathtaking," he will say. "It could represent about £20bn worth of business for UK companies."

Mr Hutton will stress that politicians have a "critical two-year window" to "clear a path" by removing regulatory and other obstacles to nuclear power.

The speech demonstrates the government's decision to confront opponents of its energy policy by trying to make the case for new nuclear power in terms of its economic impact. Ministers have previously focused on the perceived benefits of nuclear in tackling climate change and improving energy security, by providing a low carbon source of electricity and reducing the reliance on imported gas.

But Mr Hutton will present the argument in terms of the jobs and wealth that could be created, drawing a direct parallel with the economic boom triggered by North Sea oil. The emphasis on jobs, delivered in a speech to Unite, Britain's biggest union, reflects min-isterial hopes of building enthusiasm for the -ambitious new nuclear -programme among Labour's traditional support base.

The UK wants to become a leader for exporting nuclear skills, as well as building a strong domestic base of jobs, the speech will suggest.

"I want Britain to be leading the world in the development and application of this new generation of low carbon power technology. It could position the UK as the gateway to a new nuclear renaissance across Europe."

Gordon Brown is expected to take the first step to encourage this "renaissance" tomorrow, by using his summit with Nicolas Sarkozy, the French president, to announce co-operation on nuclear development. Britain's last nuclear reactor for research and training will soon be shut after failing to secure enough commercial funding, it has emerged, just as government tries to encourage rapid growth in the industry, writes Ed Crooks . Imperial College London said its Consort reactor at Silwood Park in Berkshire was more than 40 years old and unsuited for modern nuclear research. But its closure highlights Britain's shortage of nuclear research facilities.