Rhodri Morgan, the First Minister for Wales, has written to the Secretary of State for Trade and Industry, Alistair Darling, imploring him to intervene to prevent Rio Tinto from pulling out of the UK with the loss of over 500 jobs.
The mining giant has a majority stake in Anglesey Aluminium Metal (AAM), which has been in operation since 1971 and is Rio Tinto's only UK facility. But the planned decommissioning of the nearby Wylfa nuclear reactor, and rising energy costs, means the smelting plant is likely to close.
After meeting AAM's management last month, Mr Morgan wrote to Mr Darling asking him to broker a meeting between AAM and the owner of the reactor, the Nuclear Decommissioning Authority (NDA).
AAM has an electricity supply contract with the ageing Wylfa plant which fixes prices until September 2009. The NDA is in talks with AAM about signing an extension to provide electricity up until the closure of Wylfa, in December 2010, but the two sides have yet to reach agreement. Since the existing supply contract was signed, electricity prices have soared.
Aluminium smelting is highly energy intensive - the plant takes 250MW, a quarter of the reactor's capacity - and electricity is the highest biggest cost.
Plants typically source their electricity directly from a power station because they need a guaranteed supply.