A picket line of more than 200 striking employees has blocked trucks from entering or leaving a major Woolworths distribution warehouse in Melbourne's west.

The workers at the supermarket giant's liquor distribution centre in Laverton began the snap protest shortly after 4am on Monday amid rising anger over attempts to introduce labour hire casualisation.

A snap picket line outside Woolworths liquor distribution centre at Laverton. Credit:Jason South

A group of employees met with management to table demands for the company to guarantee it would not use agency labour hire or take disciplinary action against anyone involved in the picket.

Woolworths is seeking orders to break the picket line and will make its case at the Fair Work Commission on Tuesday morning.