French police arrested two Greenpeace members Wednesday after an activist flew into the grounds of a nuclear power plant using a paraglider in a stunt aimed at revealing alleged security flaws.

"A Greenpeace activist arrived with a motorised paraglider around 7:40 am (0540 GMT). He flew over the plant, threw a smoke bomb and landed inside, where he was detained," police near the Bugey plant in southeastern France told AFP.

The second person was arrested outside the plant on suspicion of helping guide the pilot, police said.

The environmental activist group said the action was aimed at the two men vying for the French presidency in a run-off vote Sunday—President Nicolas Sarkozy and his Socialist rival and opinion poll frontrunner Francois Hollande.

"The purpose of this action is to send a message to the two candidates in the presidential election who are denying the risk of nuclear power," Greenpeace spokeswoman Sophia Majnoni told AFP.

"We wanted to illustrate an external danger, like a fall of an airplane" into a nuclear plant, she said.

The EDF energy firm that runs the country's nuclear plants said in a statement that the safety of the Bugey plant was at no time compromised by the stunt.

In December, Greenpeace activists broke into two nuclear power plants in France in an action the group said was aimed at exposing the vulnerability of the facilities.

Nine activists broke into the Nogent-sur-Seine plant near Paris and two into the Cruas plant in southern France.