Workers at the Port Kembla Coal Terminal have been locked out again as the company continues to take a hard line on its industrial dispute with union members.
The workers, understood to number about 60, will be denied entry until the weekend.
Members of the Construction, Forestry, Mining and Energy Union will protest outside the coal terminal from Friday morning.
Details of the return time were not immediately available.
The second lockout – the first was just over a month ago – shows the bitterness of the dispute.
Workers started a series of industrial action at PKCT before Christmas.
The company responded with a four-day lockout in January.
The action is taking place as a new enterprise bargaining agreement is negotiated.
PKCT has applied to have the existing enterprise agreement terminated.
Comment has been sought from the CFMEU and the PKCT.