The UK government was today accused of lobbying to water down new EU legislation designed to accelerate the deployment of renewable energy capacity and ensure the bloc's target of generating 20 per cent of energy from renewable sources by 2020 is met.

The Guardian newspaper says it has obtained leaked documents showing that at a time when Gordon Brown has vowed to deliver a "green revolution", UK officials are attempting to weaken tough proposed EU legislation designed to prioritise the development of renewable energy capacity.

The EU renewables directive is being discussed in Brussels and is intended to provide the legal framework to support the EU's push to ensure that a fifth of all energy comes from renewable sources by 2020. One proposed requirement of the directive is that "Member states shall also provide for priority access to the grid system of electricity produced from renewable energy sources."

Industry figures in the UK have repeatedly claimed that slow progress in connecting renewable energy projects to the grid is one of the key factors hindering development and the intention is that the requirement would force governments to ensure the grid infrastructure is quickly put in place to support renewable energy projects.

However, the documents obtained by the Guardian show Britain wants to change the wording of the requirement, substituting "member states shall also provide priority access to the grid…" with "member states may also provide priority access to the grid…" – a move experts claim would make the requirement virtually meaningless from a legal perspective.

Claude Turmes, a Luxembourg MEP who has worked on the directive, accused the UK government of hypocrisy. "This would take us backwards and would weaken the possibilities of connecting renewable energy to the grid," he told the Guardian. "A government that says it wants to promote renewables cannot go for other policies behind the scenes."

However, the government insisted that its proposed change to the legislation was justified, arguing that giving priority grid connection to all renewable energy projects could undermine the stability of the grid and leave it too reliant on intermittent renewable sources of energy.

A spokeswoman for the Department for Business, Enterprise and Regulatory Reform (BERR) added that the government remained committed to ensuring renewable energy sources are connected to the grid quicker.

"What renewable generators want is quicker access to the grid, not priority access," she said. "The UK is already taking significant steps to remove grid access barriers for renewables. It is, however, important that all forms of generation have faster access to the grid network to ensure a balanced and secure energy supply."

However, critics of the government's renewable energy strategy are likely to detect a pattern in reports that officials are seeking to water down renewables requirements.

Leaked documents last year revealed BERR had warned the prime minister that meeting the EU's 20 per cent target would present "severe practical difficulties " and had suggested that the targets be lowered. Environmental groups have also criticised the government for campaigning for a renewable energy trading scheme that would allow renewable energy projects funded in other countries to count towards the UK's performance.