Dock workers confronted riot police during a protest over wages and conditions at Port Botany as part of a 24-hour work stoppage.
About 100 members of the national maritime union who work for stevedoring giant Hutchison Ports in Sydney marched from its car park to Patrick Port Botany Terminal.
Union members posted videos on the Maritime Union of Australia Sydney branch Facebook page and said that branch secretary Paul McAleer had been arrested and then released shortly after. The workers said they were protesting to protect their jobs at Hutchisons.
It is understood the company was notified on Saturday of the 24-hour stoppage between 6am Thursday to 6am Friday. Hutchison Ports made an application to the Fair Work Commission to extend the notice period the union must provide before taking any industrial action to five days.
The company raised no concerns about major disruptions as its negotiations with the union continued on Wednesday and Thursday in Brisbane.
Union employees are taking protected industrial action over a new wage agreement as Hutchison, which lost tens of millions of dollars in the past financial year, seeks to drive down costs.
The existing wage agreement pays waterfront workers an average of $150,000 in Sydney and $130,000 in Brisbane for working 30 to 33 hours a week, plus 12 per cent superannuation.
Hutchison is proposing to reduce the superannuation benefit to 9.5 per cent and introduce a fixed term wage freeze.
The union accuses Hutchison of wanting to slash wages by up to $10 an hour followed by a pay freeze, followed by a wage rise of one per cent per year. It says cuts to redundancy and long-service leave and paid parental leave were also planned.
Maritime Union of Australia assistant secretary Warren Smith said its members refused to sit back and watch as four-decades of hard-won conditions were "stripped away".
He said the union will use "every industrial and legal tool at our disposal in our fight to protect conditions and safety standards on the waterfront".
Hutchison Ports declined to comment on Thursday as negotiations with the union continued.
In 2015, workers for Hutchison walked off the job in NSW and Queensland after the company sacked 97 workers by emails and text messages. Hutchison withdrew the job cuts in response to the strike action. The company and union later reached an agreement to allow for 60 voluntary redundancies and improved redundancy entitlements.
Meanwhile, the CFMEU announced on Thursday evening that Port Kembla Coal Terminal workers will strike for seven days from Saturday after negotations with management stalled over the the new enterprise agreement.
Anna Patty is Workplace Editor for The Sydney Morning Herald. She is a former Education Editor, State Political Reporter and Health Reporter. Her reports on inequity in schools funding led to the Gonski reforms and won her national awards. Her coverage of health exposed unnecessary patient deaths at Campbelltown Hospital and led to judicial and parliamentary inquiries. At The Times of London, she exposed flaws in international medical trials.