Workers at a Newcastle coal terminal have endorsed ongoing industrial action after striking over what they say is a threat to their work rights.
Over 200 employees of Port Waratah Coal Services (PWCS) attended a four-hour rally in Newcastle on Wednesday where they unanimously voted for a two-week campaign of protected action.
The action will include eight, 12 and 24 hour stoppages as well as bans on overtime and working outside classifications, the unions representing them said in a joint statement.
PWCS's current offer removes limits on the use of contractors and gives employees less say over work hours and shifts, The Maritime Union of Australia (MUA), Transport Workers Union (TWU), Electrical Trades Union (ETU) and Australian Manufacturing Workers Union (AMWU) say.
Talks between the PWCS and unions will continue next week.
Comment was being sought from PWCS, which has previously said it was seeking productivity and flexibility trade-offs against significant pay increases for workers.
A MUA spokesman said his members couldn't understand why the relationship with PWCS had soured.
"We've enjoyed a mutually beneficial relationship for many years," he told AAP.
"We just don't understand why after 30 years of a good relationship they've decided to reduce conditions of employment."
A PWCS spokesman said the company had not received any immediate notification of pending action.
Wednesday's four-hour stop-work caused the company minimal disruption, he said.
The United Steel Workers in the USA have sent a letter of support to PWCS Workers.