THE loss of hundreds of jobs at a pharmaceutical giant is “potentially devastating”, a union has warned.

GlaxoSmithKline (GSK) has announced it is planning to shed a third of the workforce at its plant in Southdown View Way, Worthing.

Some 246 staff are facing redundancies out of 672 currently employed by the firm in the town.

The move is part of a UK-wide restructure by GSK, which will lead to it outsourcing some of its antibiotics manufacturing currently done at Worthing.

Other plans include selling off GSK’s malt drink Horlicks brand and the closure of one of its sites in Berkshire.

The redundancies will be made over the next four years.

Unite has about 1,000 members nationally within GSK, including 185 members at Worthing.

Regional officer Mick Pollek said: “This is both extremely concerning news and potentially devastating for the workers and their families.

“It had appeared that GSK was investing significantly at the Worthing operation and now these job losses are suddenly announced.”

Unite national officer for the pharmaceutical industry Tony Devlin said: “We will be meeting with the UK senior management next week to discuss the reasons behind this announcement which has come as a significant blow for Unite members.

“We will be looking at the detailed business case for these proposed redundancies and changes in national strategy.

“These are skilled jobs that are under threat and we can’t afford to lose such manufacturing posts, with the economic challenges of Brexit looming.

“We will be fighting very hard against any proposal for compulsory redundancies and will be offering the union’s maximum support to our members in the days and weeks ahead at what is a very challenging time.”

Worthing Borough Council’s executive member for regeneration Kevin Jenkins said: “We are disappointed to hear the news from GSK but obviously recognise that all businesses have to undergo reorganisation from time to time.

“We welcome GSK’s commitment that they remain committed to Worthing with a large operation of more than 400 jobs and will continue to maintain dialogue with them.

“As a council we will also continue to push our regeneration and economy agenda to draw in more investment and jobs into the town as a whole.”

GSK says none of the decisions are due to the UK’s decision to leave the European Union.

It said the moves were necessary to improve productivity and overall business performance.