(CNN) -- The company that runs a nuclear plant in eastern France said no one was injured in a vapor release at the site Wednesday, despite earlier reports that two were hurt.
In a tweet, Electricite de France initially said two people's hands were slightly burned when oxygen was released during maintenance work at the Fessenheim site near Mulhouse. But in a later statement on its website, the company said that all nine workers in the area of the vapor release were checked and no one was injured.
Although the situation was not serious, an investigation is needed to find out why the accident happened, said Thierry Charles, the deputy director general in charge of nuclear safety for the Institut de Radioprotection et de Surete Nucleaire. The IRSN is an independent government agency that oversees nuclear safety in the country.
The site has been the subject of controversy in France. President Francois Hollande promised during his campaign to close it by the time his term ends in 2017, citing security concerns in the wake of a disaster last year at the Fukushima Daiichi plant in Japan. Some in France have called for him to keep it open.
The complex is France's oldest nuclear site, housing two 900-megawatt reactors. It became active in 1977.
CNN's Alanne Orjoux and Stephanie Halasz contributed to this report.