A leaked memo from BVT says up to £500m could be saved by closure of two of the three yards at Scotstoun and Govan on the Clyde and Portsmouth.
But Prospect negotiator John Ferrett described the statement as a “betrayal by both BVT and the government if the closures go ahead.”
Ferrett said: “Prospect was at the forefront of lobbying for the award of the carrier contract to BVT on the understanding that this would safeguard members jobs within the shipbuilding industry for at least 15 years.
“Instead, this announcement emphasises cost savings rather than winning new business and guaranteeing employment in Portsmouth and the Clyde.”
Ferrett warned that closure of the yards could result in many thousands of job losses and would decimate what remains of the shipbuilding industry in the UK.
“The government has a duty to protect the defence industrial infrastructure and the skills base that goes with it. The UK needs to be positioned to take advantage of an economic upturn. Abandoning skilled workers, who will be the backbone of any recovery, is not the way to do it,” said Ferrett.
Prospect represents 18,000 managers and specialists in the UK defence sector.