MONTREAL -- Industrial valve maker Velan Inc. (TSX:VLN) has locked out about 400 unionized employees at three Montreal plants where a tentative collective agreement was rejected.

The company says it acted because the union launched pressure tactics such as work slowdowns and other disruptions that it said posed health and safety concerns.

Velan says it was surprised by the 78 per cent vote against a new labour agreement that provided 2.5 per cent annual wage increases for three years.

Workers in Granby, Que., which has about 100 employees, voted 90 per cent in favour of the agreement.

The union says certain parts of the agreements that gave the company additional labour flexibility were different at the Granby and Montreal locations.

Velan employs more than 2,000 people at manufacturing plants in 11 countries.