PARIS, Jan 7 (Reuters) - A major aluminium smelter in northern France is to reduce production by 15% in response to soaring electricity prices, a spokesperson for the site said on Friday. The smelter at Dunkirk, which has annual capacity of about 285,000 tonnes, has already cut output by 10% and will reduce it by a further 5% next week, the spokesperson said. Dunkirk is one of several aluminium plants in Europe to lower production since last month in response to record electricity prices that have hurt margins for the energy-intensive industry. The spokesperson declined to comment on possible additional production cuts. A CGT union official at the site, Laurent Geeraert, told local radio station Delta FM that cuts would be amplified to around 25% of capacity if electricity prices didn"t ease. The Dunkirk smelter is among large energy users discussing relief measures with the French government and state-owned EDF (EDF.PA), which operates the country"s nuclear power network. Dunkirk obtains about 60% of its electricity through a preferential rate scheme, but is exposed to market prices for the remaining 40%. France"s finance minister said on Friday he was working on further measures to limit the surge in electricity prices, with the government mindful of the burden on consumers ahead of April"s presidential election. read more Private equity firm American Industrial Partners (AIP) acquired the Dunkirk smelter last year following a debt default by a unit of previous owner GFG Alliance. The takeover is being challenged by GFG, which is owned by commodities tycoon Sanjeev Gupta. read more