French energy group EDF on Thursday announced a further delay to the launch of its next generation EPR nuclear reactor, another setback for its 10.5-billion-euro ($11.6 billion)  project.

The launch is now set for "the fourth quarter of 2018," said EDF CEO Jean-Bernard Levy, of the showcase project being built with atomic energy giant Areva which has faced fresh technical problems in the past few months.

It's the fourth time EDF (Electricite de France) has had to push back the delivery date of the European Pressurised Reactor (EPR), a third-generation reactor design considered the most advanced and safest in the world.

The project in Flamanville in northwest France, which began construction in 2007, was set to be the first EPR reactor to go on line, but now it appears that could be achieved at the Taishan nuclear reactor in southern China.

Another EPR project in Finland, involving Areva and German engineering group Siemens, has also been plagued with delays and cost overruns. It is set to begin the testing phase in 2016 and start operations in 2018.

Levy put China's racing ahead to be first with an EPR reactor down to differences in nuclear security regulations as well as building and labour practices.

China, which started construction in 2009, has also "greatly benefitted from the experience at Flamanville", which has allowed it "to avoid some of the glitches," said Xavier Ursat, director of engineering and new nuclear projects at EDF.

Flamanville was originally set for delivery in 2012 at a budget of 3.3 billion euros. The latest setback leaves the estimated cost at

10.5 billion euros.

"The cost of the first model is always higher," said Levy.

He also stressed that EDF and Areva remain confident of the reactor, which is "vital" for France's electricity network and can help the renewal of the country's vast nuclear energy sector.

France is the most nuclear-dependent country in the world, and the second-biggest producer of nuclear energy with 58 reactors located in 19 power stations.

The delay and increased cost overruns sent EDF shares tumbling 2.24 percent Thursday to close at 18.290 euros on the Paris bourse.