An explosion at a major nuclear site facility in the south of France has resulted in the death of one person and caused injuries to four others, with one in a serious condition.

The site in Marcoule, part of the Languedoc-Roussillon region of France, was opened in 1955, making it one of France's oldest nuclear sites. According to officials, the blast was caused by a fire near a furnace in the Centraco radioactive waste storage site at 11.45am (9.45am GMT).

The nuclear plant, located close to France's Mediterranean coast, was initially set up to produce plutonium. It has since been involved with the decommissioning of nuclear facilities, now recycling plutonium from nuclear weapons.

The treatment centre currently belongs to a subsidiary of national electricity provider Eléctricité de France (EDF). In response to the news concerning the explosion in Marcoule, EDF experienced a drop in share prices by 6 per cent.

A spokesman for France's Atomic Energy Commission (CEA) has reassured the public that "for the time being nothing has made it outside" and officials at the site have said that there were no radioactive leaks after the blast.

At present, nuclear power is the primary source of electric power in France, providing for 70 per cent of the country's energy needs. Following the disaster at the Fukushima nuclear plant in Japan earlier this year, all of France's 58 nuclear reactors were put through stress tests in recent months.