Dame Joanna Lumley and actor Ralph Fiennes have warned in a joint letter that two planned wind farms off the Suffolk coast could see an area of beautiful countryside "disappear under a sea of concrete".

Comedian and television presenter Griff Rhys Jones, who has a home in the county, is also among the 17 signatories to the letter published in The Times on Monday.

ScottishPower Renewables (SPR) said its planned East Anglia ONE North and East Anglia TWO offshore wind farms would generate enough electricity to power more than 1.4 million UK households.

Underground cables would transport the electricity to onshore substations, with decisions on whether to grant development consent to the two applications due by March 31.

The letter said: "A vast tract of Suffolk's most beautiful countryside is slated to disappear under a sea of concrete with ScottishPower Renewables (SPR) and National Grid's destructive plans to build potentially the largest onshore energy hub in Europe.

"National Grid failed to present the true scale of their projects to the Planning Inspectorate.

"The energy minister's imminent decision on East Anglia ONE North (EA1N) and East Anglia TWO (EA2) will enable six further towering structures, sacrificing land at Snape, close to the 6th-century Anglo Saxon cemetery and home of Benjamin Britten's Snape Maltings Concert Hall.

"A split decision is suggested, to continue building wind turbines but to pivot to offshore integrated cabling to brownfield sites.

"SPR and National Grid covetously call Suffolk's heritage coast 'the energy coast'.

"They threaten fragile ecosystems, diverse wildlife, Aldeburgh and the thriving local tourist economy.

"Planned industrialisation on this scale is a national issue and anything but green."

The two proposed wind farms would have up to 142 turbines in total and power would come to shore in the Thorpeness area.

A spokesperson for ScottishPower Renewables said: "As a responsible developer, we've undertaken significant consultation and engagement with local stakeholders and communities on our East Anglia ONE North and East Anglia TWO projects.

"We've continued to listen to local communities and stakeholders and take account of their feedback, adapting designs accordingly.

"This extends to our considered efforts to protect the local environment and minimise the potential onshore impacts of the construction programme."

East Anglian Daily Times: The Gunfleet Sands Wind Farm off Clacton-on-Sea.The Gunfleet Sands Wind Farm off Clacton-on-Sea. (Image: Archant)

They added that the projects have the "potential to support thousands of jobs during construction, create long-term skilled jobs, support the local and UK supply chain, deliver community benefits and play an important role in meeting the Government's offshore wind ambitions and helping tackle the climate emergency".

A National Grid spokesperson said: "After a thorough site selection and consultation process the connection location was identified by ScottishPower Renewables and put forward as part of their planning application.

"We, along with the other parties involved, now await the decision of the Secretary of State.

"The Government have set an ambition for 40GW of offshore wind power by 2030, which forms part of their legally binding target of net zero emissions by 2050.

"This growth in offshore wind power also requires reinforcement of the onshore network and National Grid is working in partnership with all parties involved to explore options for coordinating projects to reduce the impact on local communities and the environment.

"We recognise the scale of development related to the East Coast and where projects are taken forward we work hard to engage with local communities and listen to their concerns."

The East Anglia ONE project, with up to 240 turbines, was given the green light by the Government in 2014, and East Anglia THREE, with up to 172 turbines, was approved in 2017.

Earlier this month, the Energy Secretary approved a wind farm development off the Norfolk coast, ruling that the need for renewable energy outweighs concern over the "substantial harm arising from landscape and visual issues".

Vattenfall's 1.8-gigawatt Norfolk Vanguard offshore wind farm will have up to 158 turbines.

Vattenfall said that, together with the Norfolk Boreas offshore wind farm that was awarded planning consent in December, it will produce enough electricity to power the equivalent of 3.9 million UK homes.