The firm says pharmaceutical contracts will end later this year
A chemical plant employing 65 people is set to close on Anglesey after nearly 40 years.
The Eastman Chemical Company is halting production of vitamin E at the Peboc site on the outskirts of Llangefni.
The US-owned firm has confirmed that the site will close later this year and all workers will be made redundant.
The Welsh Assembly Government said it has been in close contact with the company, and officials are in negotiations to try to find a buyer.
The factory was set up on Anglesey in 1970 after relocating from London. It was bought by the American owned Eastman company in 1995.
As well as making vitamin E, the Peboc site also supplies other pharmaceutical ingredients. But the company said those contracts would end this year.
Managing director Peter Roberts said the decision to close the factory followed a consultation period which was announced in February.
"Final decisions around the timing of the site closure are still being determined, however, we do expect to exit the site later this year," said Mr Roberts.
"This site is no longer strategic for Eastman, nor does it fit the company's current plans for growth.
Mr Roberts said the company would honour all its legal obligations to staff being made redundant, including protecting pensions.
"On behalf of Eastman, I want to thank the men and women of Peboc for their many contributions over the years," added Mr Roberts.
"I especially commend them for their continued focus on doing good work during a time of great uncertainty. The decision to close this site was a difficult one."
While the chief executive of Anglesey Council described the news as a huge blow for the town and the island, a spokesperson for the Welsh Assembly Government said there had been lengthy talks with senior management at the site.
"We fully appreciate the potential impact that the closure of the plant will have on the community," said the spokesperson.
"We are working with the company to find alternative employment for its employees. Some have already been helped to secure jobs locally."
The hope has also been raised that a buyer could be found for the factory.
The assembly government's spokesperson added: "Assembly officials are also currently in negotiation with several interested companies which we have identified as a possible new, job-creating user of the Llangefni site."