Thomas Piquemal's shock resignation in March raised doubts about EDF's ability to finance the 18 billion pound project in western England but Piquemal had not previously spoken publicly about his reasons for leaving.

"In January 2015, I proposed to negotiate a three-year delay with our client because we reasoned that it would weigh too heavily on EDF's balance sheet," Piquemal told a parliament committee hearing.

A visibly emotional Piquemal said he resigned in desperation when it eventually became clear that he would not be able to delay the project.

"I could not sign off on a decision that could one day put EDF in the same situation as Areva, having to recapitalise the company a few months before defaulting on payments," he said.

Nuclear group Areva -- which has agreed to sell its reactor business to EDF -- was virtually bankrupt after years of losses wiped out its equity and was rescued by the state.

Piquemal denied reports that he had resigned for personal reasons and said that staying at the utility without speaking out about the risk involved with Hinkley Point would have been "a professional mistake".

"Who would bet 60 to 70 percent of his equity on a technology that has not yet proven that it can work and which takes 10 years to build," he said.

Four Areva-designed EPR reactors of the same kind EDF wants to build in Britian are under construction in France, Finland and China and are years behind schedule and way over budget.

Piquemal declined to comment on technical issues, but said the EPR involves a "major construction risk".

Since Piquemal's resignation, EDF has announced a four billion euro capital increase and the government has agreed to forego cash dividends for two years, in a capital boost estimated at generating around 7 billion euros.

(Additional reporting by Bate Felix; editing by Jason Neely)

By Geert De Clercq and Benjamin Mallet