£1bn Pembroke Power Station faces EU permits probe
The European Commission has launched an investigation into the UK government's approval of a £1bn gas-fired power station in Pembrokeshire.
Pembroke Power Station, the largest of its type in Europe, opened last month and will power 3.5m homes.
Following a complaint by Friends of the Earth, the Department of Energy and Climate Change has been told to clarify the impact on Cleddau estuary water.
The government said it was currently considering its response.
Water from the estuary is used to cool gas turbines at the 2000MW power station, owned by RWE npower.
Friends of the Earth (FoE) Cymru registered a complaint with the European Commission in July 2010 over concerns that EU laws had been broken.
An investigation has been ongoing since then to determine whether the Environment Agency should have issued an operating permit.
Environmentalists are concerned that three EU rules may be being breached by the site's permit to extract water from the Cleddau - to cool five gas-fired turbines - and then return it 8C warmer to a marine special area of conservation.
FoE Cymru director Gareth Clubb said the formal notice by the authorities in Brussels raised the prospect of RWE npower having to fit a new cooling system at the power station.
He told BBC Radio Wales: "Our involvement has mainly been to point out the failings of the UK government and the European Commission is now following the paper trail.
"If the European Commission determines that the UK government has breached environmental regulations then, as we understand it, the ultimate sanction could be that the whole process is determined as being unlawful.
"It's possible the company might be required to have an different cooling system installed.
"It's quite a serious situation for the UK government and we're delighted that the European Commission has taken this case because only one in five complaints of this nature actually get through to the formal notice stage."
A spokesman for the Department of Energy and Climate Change told BBC Wales that the commission's action is a "notice of infringement" and not a 'full-blown infraction proceedings".
A spokesman said: "The government has two months to respond and we are currently considering our response."