Young's Seafood is to close Pinneys fish-processing plant in Dumfries and Galloway, putting 450 jobs under threat.

The Annan factory had been earmarked for closure earlier in the year after the company said it was grappling with "exceptionally challenging" market forces.

After a 45-day consultation, the owners said they had found no viable alternative for the plant.

The factory is expected to close towards the end of 2018.

The natural salmon production is expected to be shifted from the site to a factory in Grimsby, creating 200 new jobs.

Young's, Britain's biggest seafood producer, was itself put on the market by its owners Lion Capital, Bain Capital and HPS Investment Partners, in April.

A spokeswoman said: "Unfortunately, having explored this in detail for some time and despite the consultation process, we have not been able to agree any viable alternatives to the closure of the Pinneys site.

"Accordingly, the company now intends to progress with its initial proposals.

"The decision to close the Pinneys site does not mean that collective consultation has ended.

"We intend to continue to meet with employee representatives on a fortnightly basis to discuss ongoing items, including redeployment opportunities."

Scottish Government business minister Paul Wheelhouse said the decision was "extremely disappointing" while Scottish Secretary David Mundell branded it "devastating".

Mr Wheelhouse said: "Today's confirmation by Young's Seafood that it will proceed with the closure of the Pinneys site in Annan is not unexpected, but still extremely disappointing and will quite clearly be a bitter blow to the employees, their families and the wider community.

"Despite our best efforts and offers of support to encourage Young's to retain some production at the site it recently became clear that Young's were focused on extracting themselves from the site to concentrate the natural salmon production on Grimsby.

"As such, the Scottish Government and our partners in the action group will continue to work tirelessly to identify and support any potential new investor to the site.

"We have held initial discussions with all interested parties and this dialogue will continue over the next few days and weeks in an effort to support more detailed discussions with potential buyers of the site and keep production at the site with the objective of retaining as many jobs as we can in recognition of the economic impact on Annan and the surrounding area."