The 400 staff at Cambuslang are among a 2300-strong Scottish workforce which faces an uncertain future after food giant Vion announced shock plans to put its entire UK operation up for sale.
The move came just weeks after the firm announced the closure of its Hall's of Broxburn plant, with the loss of 1700 posts.
Finance Secretary John Swinney accused the Dutch firm of keeping the Scottish Government in the dark after Vion failed to provide officials with details of its plans for its 12 other Scottish sites during the failed talks about the future of the Hall's plant.
Outwith the Hall's of Broxburn operation, the firm employs around 2300 workers in Scotland, including 50 at the UK branch's head office in Livingston.
Mr Swinney said: "This is an extremely disappointing ann-ouncement. I recognise this will be a particul-arly worrying time for Vion employees."
Rural Affairs Secretary Richard Loch-head said: "Clearly this news will be a concern for Scotland's farmers, Vion employees and suppliers, particularly coming hard on the heels of the Hall's of Broxburn closure."
The meat-processing giant said it remains confident it will successfully sell all 38 of its UK sites, which employ 13,000 workers.
Vion UK chairman Peter Barr said: "We have started detailed discussions with a number of interested parties, including management."