The French utility giant recently pushed back the decision once again to at least September. De Rivaz had assured it would be taken "very soon" when he appeared before the energy and climate change committee about two months ago.
"There's a feeling that the can is being kicked down the road constantly by EDF. People have a right to know one way or the other," Angus Brendan MacNeil, chair of the energy and climate change committee, told City A.M.
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The committee will also push EDF on other possible impediments to the project, while energy minister Andrea Leadsom will be grilled over how the government will ensure Britain's longer-term energy security if Hinkley falls through.
The final investment decision was widely expected to be taken in January, but it's been repeatedly delayed as EDF struggles to find partners and financing.
There's also growing concern over whether the project, which is crucial to the government's energy policy, will go ahead at all. France's energy minister, Ségolène Royal, has questioned whether France should proceed with it, while EDF's chief financial officer Thomas Piquemal resigned due to funding concerns earlier this year.
“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,” Thomas Piquemal recently told a French parliament committee hearing. “Who would bet 60 to 70 per cent of his equity on a [European pressurised reactor] technology that has not yet proven that it can work and which takes 10 years to build.”
EDF, which has debts of €37bn (£28.6bn) is awaiting a bailout from the French government. It recently posted a 68 per cent plunge in net profit due to asset impairments, while slashing its dividend.
De Rivaz last appeared before the committee on 23 March.