Wildcat strikes have returned to the Lindsey oil refinery after hundreds of workers walked out over planned job cuts.
Employees at the north Lincolnshire depot downed tools yesterday after being told that around 50 workers would be made redundant.
Lindsey oil refinery, which is owned by French energy giant Total, was hit by a series of strikes earlier this year over the use of foreign labour.
A company spokeswoman confirmed workers were striking over the job cuts, but said that the action would not affect the refinery.
"A number of construction workers have walked out, but it's not the whole workforce," she said.
Paul Kenny, general secretary of the GMB union, said "local discussions" were under way to try to resolve the dispute.
"There are concerns that these workers may be being victimised for earlier industrial action and that these redundancies are in breach of the agreement that brought industrial peace to the site some months ago," he said.
Employment experts have warned that the number of wildcat strikes are likely to rise as union membership wanes.