About 300 people joined a “walk for jobs” to protest against redundancy plans at an aircraft engine maintenance plant.
General Electric (GE) announced in July that it plans to cut 369 jobs at its site in Nantgarw, near Caerphilly.
A further 180 posts have already been lost since the coronavirus crisis began through voluntary redundancies.
Organiser Caerphilly Trades Council urged those taking part to social distance and wear masks.
The protestors gathered near Caerphilly Castle for the midday event.
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GE has been consulting with 1,400 staff at Nantgarw, as the firm suffers from the drop of numbers in air travel.
The company, which makes jet engines for Boeing and Airbus, has blamed the “unprecedented impact of Covid-19”.
It has said it remained focused on “preserving our capability to respond as the industry recovers”.