France on Tuesday took a key step towards shutting down its oldest nuclear power station, a campaign promise of Socialist President Francois Hollande, just months before he leaves office.

The board of state-owned electricity utility EDF approved a compensation package worth at least 400 million euros ($430 million) for the shutdown of the Fessenheim nuclear plant, a source close to the matter said.

EDF, which is 85.6 percent owned by the state, agreed the plan with the French government last August.

The closure of the twin-reactor plant is part of a plan to dramatically reduce the country's dependence on atomic energy.

The plant in Fessenheim on the border with Germany about 100 kilometres (60 miles) south of Strasbourg has been in operation since 1977.

Fessenheim, located on a seismic fault line, has worried French, German and Swiss environmentalists for years.

Hollande, who leaves office in May, vowed during campaigning in the 2012 election to close the facility, as part of a promise to reduce the share of nuclear in France's energy mix from 75 percent to 50 percent and increase the share of renewables.

But the plan ran into stiff opposition from the conservative opposition, which sees France's nuclear park as a guarantor of the country's energy independence and a source of cheap electricity.