More than £650m worth of nuclear contracts have been awarded to East of England companies for a nuclear power plant project which is set to provide the template for Sizewell C, it has been revealed.

Some of the region's contracts working on Hinkley Point C in Somerset - where building work is moving on apace - are also involved in early work on the Leiston scheme, which is at a much earlier stage of development.

Among the firms in the region involved in the Hinkley supply chain are Ipswich-based law firm Birketts and Colchester water filtration company Ovivo, both of which have also been appointed to the proposed Sizewell C project, said energy firm EDF.

The biggest Hinkley contract secured in the region is with Kier BAM, based at Sandy in Bedfordshire, which is carrying out £500m worth of earthworks. The remainder of the £150m worth of contracts are spread across Suffolk, Norfolk and Essex firms.

The most significant spend on Sizewell C has been with companies supporting the investigative work on the project such as Lowestoft marine surveyors Cefas, but as the project progresses, contracts are now being awarded for early enabling work such as with Ovivo.

Birketts will work alongside Thetford-based Dalcour Maclaren, which were appointed by Sizewell C earlier this year, to work with local landowners. It will also support contract management for early site preparation work.

Ovivo has a £27m contract to supply the water filtration system for Hinkley. It is working on early design works for a similar system for Sizewell C, then hopes to turn its attention to Bradwell B. Other regional companies involved in Hinkley Point C include, concrete specialists Poundfield of Ipswich, and Newmarket steel firm AJN Steelstock in Newmarket.

Sizewell C boss Jim Crawford said: "We are delighted to work with more local companies on both Hinkley Point C and the Sizewell C project. This is just the beginning, as we can see at Hinkley Point C where spend with local businesses in the South West has now topped £1bn."

Birketts' head of property Chris Schwer said: "We are pleased to support the development of the Sizewell C proposals through sensitively managing land agreements in this area. This is an area in which we have a good deal of local knowledge that we hope to build on further with the Sizewell C project."

Jeremy Lee, Ovivo Sales Manager, said: "We are very pleased to work on plans for Sizewell C following the major work we have completed for Hinkley Point C in Somerset. Ovivo also built the water filtration system used at Sizewell B so we are proud to build on our heritage in this area."

Other firms involved in the Hinkley supply chain are Ipswich businesses Sharps Redmore, Red7Marine and Capco Test Equipment Ltd, Chemtest of Newmarket, Geosense Ltd of Bury St Edmunds, Snelling Business Systems Ltd of Wymondham, Norwich-based Norwich Instrument Services and Althon Ltd and Stuart Group Ltd of Shropham.