In a statement before its shareholder meeting today, the energy giant admitted the projected cost of the plant had a “contingency margin” that could see the price tag rise from £18bn to £20.7bn.

This margin would involve EDF’s share of the financial commitment for the Somerset plant rise from £12bn to £13.8bn, while that of its partner China General Nuclear Power Corporation would increase from £6bn to £6.9bn.

The company also revealed a construction timetable that could see the nuclear plant miss its projected 2025 completion date.

EDF’s statement confirmed a 115-month construction period from the date of a final investment decision.

However, with that decision not expected before September following a series of delays, the timetable would take completion beyond the original 2025 deadline and into spring 2026.

A source at EDF UK said it still expected the project to meet the 2025 completion date.