The issue was raised by the government as it applied to the European Union (EU) for special conservation status for three estuaries – the Severn, Dee and Humber.

Joan Ruddock, biodiversity minister, said: “In submitting these sites the government has demonstrated its commitment to the protection and restoration of the UK’s richly diverse, and internationally important, wildlife habitats.

“We will work towards ensuring that our environmental protection agenda and our aim to develop renewable sources of power are complementary.”

The Department for Environment, Food and Rural Affairs (DEFRA) has written to the European Commission seeking Special Areas of Conservation (SAC) status for the three estuaries under the EU Habitats Directive aimed at protecting vulnerable wildlife and habitats.

This autumn the Sustainable Development Commission, the government’s independent watchdog, is to report on the potential for tidal power electricity generation in the Severn and elsewhere.

DEFRA says it has told the commission how Severn tidal power developments could help meet carbon emission and renewable energy targets.

But it also points out the proposals “could significantly alter the ecological characteristics of the estuary and raise issues regarding the balance between habitat protection and tackling the wider problems caused by global warming”.

It is “discussing” the balance with the commission.

If granted SAC status the estuaries will join the UK’s 611 other SACs covering some 2.5 million hectares.

The Severn Estuary is one of the UK’s largest and best areas for mud and sand flats and Atlantic salt meadows and is an important area for migratory fish and a nursery for juvenile fish.

The Dee is the fifth largest area of mud and sand flats of any UK estuary and a dune system with a rich variety of plants, which is important for migratory fish.

The Humber Estuary is the largest British coastal plain estuary on the North Sea.

It drains a fifth of England is home to many rare or threatened mammals, fish and plants.

EU countries have to submit a list of SACs to the commission in order to create a network of conservation sites aimed at protecting biodiversity.

But this status does not rule out the possibility of future development.

David Gibbs

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie