Fierce storms which hit France in April will help to push wine production down almost 10 percent this year, the ministry of agriculture said Thursday.

Unseasonably cool weather through the spring and into the summer will drag overall production down to 42.9 million hectolitres from 47.8 million a year ago, according to the ministry's statistical service Agreste.

Agreste blamed "the spring freeze that hit certain winegrowing areas, recurring winds made worse by drought around the Mediterranean and damage stemming from frost."

Champagne was one of the worst hit regions after several bouts of spring frost and hailstorms which are forecast to drag output down by as much as one third, leading to harvesting being already a week behind schedule based on a 10-yearly average.

An even larger fall is likely to beset the Loire Valley.

The inclement weather means France, which has also had to battle outbreaks of rot and mildew, will likely remain behind Italy, which last year claimed the crown as the world's biggest wine producer.

Jerome Despey, who heads the wine division of agriculture ministry offshoot FranceAgriMer, told reporters the storms and accompanying fallout had been "spectacular," with hailstorms ravaging vast swathes of wine-growing areas "with an intensity which laid waste entire vineyards" in several regions.

The cold snap will also likely cut production in Bourgogne, Beaujolais and Charentes -- which lost some 3,600 hectares -- by around fifth with harvests lagging by ten days or more.

In Languedoc-Roussillon in the deep south frost hit some 2,000 hectares and production will likely slump nine percent with harvests of Chardonnay and some rose wines down some 40 percent.

Despey said drought was taking an additional toll so some producers may bring forward their harvest "to avoid a supplementary impact" with alternate dry and rainy spells allowing mildew to thrive.

Water shortages are also having an effect, including in the Bordeaux region -- a production bright spot with a forecast rise of one percent.

FranceAgriMer meanwhile announced it had authorised the planting of some 3,500 hectares of new vineyards nationwide -- barely half the maximum allowed under new European legislation unveiled in January.