EU governments on Friday endorsed an outline deal on new rules to assess the impact on the environment of projects such as oil and gas exploration, after removing references to shale gas that had blocked agreement.

Some European nations are eager to develop shale gas as they view the United States' shale gas revolution and cheap energy costs compared with Europe as a huge competitive advantage.

But the geology in Europe is very different and public opposition is strong on environmental grounds.

Many of those keenest on exploiting shale gas, such as Britain, say extra EU regulations on the energy form are unnecessary and would get in the way of its development.

British Prime Minister David Cameron wrote to European Commission President Jose Manuel Barroso this month laying out his arguments against new rules for shale gas.

On Friday, EU ambassadors approved a revised draft law, updating legislation first agreed more than two decades ago and for the first time including an assessment of a new project's impact on climate change, EU diplomats said.

In a statement, Valentinas Mazuronis, environment minister of Lithuania, which holds the EU presidency until the end of the year, said the reforms would streamline the process and set minimum requirements across the European Union.

The proposals, endorsed by ambassadors on Friday, still need to be signed off by the European Parliament and by ministers to become law.

The parliament had called for mandatory shale gas impact assessments, but EU diplomats said negotiations between representatives of the Parliament, the Commission, the EU executive, and member states had been blocked until that requirement was dropped.

So far, shale gas is already covered by 17 different pieces of EU legislation, but there is no specific law.

A full impact assessment for a gas project is only required when a single licensing area produces more than 500,000 cubic metres of gas per day.

Shale gas, which companies such as Chevron and ExxonMobil had sought to develop in Europe, will again come up for debate in January, when the Commission is expected to publish its 2030 environment and energy strategy.

This is expected to cover shale gas, although an EU official, speaking on condition of anonymity, said any guidance on shale gas would not involve new binding law.