PARIS (Reuters) - Greenpeace activists entered several French nuclear sites on Monday to highlight what they called a lack of security at the plants six months before a presidential election . Greenpeace said its activists had managed to enter the Nogent plant near Paris early on Monday and climb onto one of the domes that houses a reactor, while others had got into other nuclear installations and were so far undetected. This is the ultimate proof that the security that is in place is insufficient ... and to what extent French nuclear plants are vulnerable, Sophia Majnoni dIntignano, in charge of Greenpeaces nuclear campaign, said in a statement. Frances dependence on nuclear energy has been much debated before the presidential election in April. France is more dependent on nuclear energy than any other country, relying on it to produce 75 percent of its electricity. The Socialist Party and the Greens struck a deal last month to shut Frances 24 oldest reactors by 2025 and not to build any more reactors if in power, marking a U-turn by the Socialists who had supported nuclear power in the 1980s and the 1990s. After the Fukushima disaster in March 2011, France along with other European countries, decided to carry out safety tests on the countrys 58 nuclear reactors to test their capacity to resist flooding, earthquakes, power outages, failure of the cooling systems and operational management of accidents. But those did not include terrorist attacks, or the possibility of a plane crash. EDF confirmed that a group of people entered the Nogent site illegally. They were immediately detected by the security system and their movements were tracked on the site, EDF said in a statement, adding EDF had decided not to use force. All nine activists had now been caught by police, EDF said. The intrusion had no impact on the safety of plants, nor on the safety of people present on the site, said the utility, which operates Frances 58 reactors.