(Updates with energy minister comments, details)
By Susanna Twidale
LONDON, May 24 (Reuters) - EDF cannot give a definitive time for when the French utility will make an investment decision regarding the Hinkley C nuclear project in Britain, EDF Energy CEO Vincent de Rivaz told British lawmakers on Tuesday.
The project, estimated to cost at least 18 billion pounds ($26.16 billion), was announced in October 2013. It is expected to produce seven percent of Britain's electricity when built, but a final investment decision has been delayed as EDF secures partners and financing.
De Rivaz told members of parliament's energy and climate change committee some of the company's trade union members had suggested the project should be delayed by 2-3 years.
The final decision would be taken once a consultation by the company's central works council had taken place.
That consultation began on May 2 and will at least 60 days, de Rivaz said, but would not say how long it could last.
"I don't want to prejudge the outcome of the consultation the sooner we have the final investment decision the better," he said, speaking in front of parliament's Energy and Climate Change Committee.
De Rivaz was called to reappear before the committee after indicating in March that a final decision could be taken by early May to explain why that had not happened.
Britain is looking to Hinkley to replace ageing power plants and to help the country meet its emission-reduction targets.
Britain's minister of state at the Department of Energy and Climate Change, Andrea Leadsom, was also called before the committee. She said the government had not given EDF a deadline to take a financial decision on the project and remained "fully confident" the project would go ahead.
De Rivaz said EDF still hopes the project will start power generation in 2025, but said an update on timings would be provided after the investment decision had been taken.
The company said this month it would take 115 months to build once the decision is made.
Both de Rivaz and Leadsom said the project would not be affected should Britain leave the European Union after a referendum on June 23.
Separately, French Economy Minister Emmanuel Macron told the British lawmakers in a letter that French authorities remained fully behind the project and he had every confidence a final investment decision could be made rapidly after the central works committee consultation.
"I can appreciate that a certain amount of impatience may be creeping in as the project is key for the UK's energy and climate policy," Macron wrote in the letter dated May 23.
The French state owns 85 percent of EDF.
$1 = 0.6881 pounds Additional reporting by Karolin Schaps; editing by Jason Neely