Gordon Brown will today give this first major speech on the environment since becoming prime minister, as he seeks to reassert the UK's position as a global leader in the fight against climate change.

In recent weeks a series of reports have accused government departments of seeking to water down environmental goals, but Brown is today expected to recommit the UK to targets for emission reductions and renewable energy generation.

He will say that further action on climate change is urgently required and stress that transitioning to a low-carbon economy could create thousands of jobs.

He will also reiterate the government's commitment to meeting the EU target of ensuring 20 per cent of energy comes from renewable sources. Last month, a leaked document from the department for Business, Enterprise and Regulatory Reform (BERR) revealed ministers had advised Brown that the targets would be extremely difficult and costly to meet and urged him to lobby other EU states for more flexible goals.

However, according to reports, Brown has been persuaded by Defra that increasing renewable energy capacity is essential if the UK is to attain the emission reduction targets to be required under the imminent climate change bill.

The government is also expected to announce new schemes to provide homeowners with more information about their houses' energy efficiency.

The speech is likely to be welcomed by green business leaders who have been calling for Whitehall to more clearly commit to establishing the regulatory and incentive-based framework required to support the transition to a low-carbon economy.

However, the speech will be somewhat overshadowed by reports this weekend that Defra, the department charged with turning much of the government's climate change policy into a reality, is planning at least £300m in emergency cuts.

According to reports in The Guardian newspaper, the department urgently needs to balance its books following a series of costly disasters, such as the foot and mouth crisis and over payment of EU subsidies to farmers.

All agencies within the department are expected to be affected, with nature conservation initiatives likely to face particularly swingeing cuts.

Businesses are also set to be affected, with the Waste and Resources Action Programme (Wrap), which provides best practice advice and support for firms' recycling and waste reduction initiatives, reported to be facing a budget freeze.