One man has been arrested at the Sydney River bridge construction site, the scene of a third day of demonstrations by union workers.

The workers are saying that contractor Caldwell and Ross Ltd. has brought in non-union labour from New Brunswick to work on the bridge project.

Protests began Tuesday, when demonstrators stormed the work site. A court injunction then ordered the protesters from Labourers International Union Local 11-15 not to enter the construction zone again.

On Wednesday, many gathered outside the gates. Roughly 50 protesters returned Thursday. The injunction has been beefed up to prevent them from getting closer than 30 metres from the entrance.

Union leaders are seeking a meeting with transportation minister Geoff MacLellan.