Britain’s Hinkley Point power station could cost £1.5bn more than initially expected, according to estimates by French energy group EDF, that come less than a year after the project received final approval.

EDF said on Monday that cost estimates were now £19.6bn following a review, adding there was risk the project could be delayed by up to 15 months, pushing the completion date long past 2025.

The admission, which follows an internal review, will add fuel to criticisms within EDF that the project unmanageable and overly risky for a company already weighed down by high levels of debt.

It will also prompt further criticism in the UK by those who believe that the deal is too expensive for British taxpayers and carries a heavy construction risk.

The other two nuclear reactor projects in Europe using the same EPR technology that will be used in Hinkley point about both wildly over budget and behind schedule.

EDF’s first attempt to build an EPR reactor plant in Flamanville, northern France, is six years behind schedule and €7bn over budget.

A project by the French group Areva in Finland is decade late and more than €5bn over budget, causing the collapse of the company.

In June, the UK government spending watchdog warned that electricity consumers face paying £30bn above market prices for a “risky and expensive” deal to build Hinkley Point.

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