Rival gang members clashed a Winz office in Dunedin yesterday afternoon.
Police were called to the St Andrew St service centre following reports members of the Mongrel Mob and Black Power were involved in a fight.
A 29-year-old Mongrel Mob member was arrested and charged with a fighting-related offence, Senior Sergeant Mel Aitken said.
The man was at the Winz office assisting a fellow gang member who had an appointment when a scuffle with the Black Power member broke out.
Inquiries were continuing as to who from the rival Black Power gang was involved, with police reviewing CCTV footage of the incident.
The men were not wearing patches at the time of the incident, she said.
Ministry of Social Development regional commissioner John Allen said "there was a brief scuffle between several members of the public yesterday in the entrance way of our office".
"However, I can confirm no-one was hurt," he said"All of our service centres and community links have security guards on site and staff are well briefed on how to handle any such situations."
Winz did not comment when specifically asked how members of rival gangs ended up in the service centre at the same time.
However, Mr Allan said Winz had "robust security procedures in place to deal with any such incidents".
The safety and security of its staff and clients were not compromised, and "we are confident we have the measures in place to ensure our offices are safe places to visit", he said.
A 34-year-old Black Power member was stabbed by a rival gang member near the Robbie Burns statue in the Octagon earlier this month.
Conflict between the rival gangs erupted two years ago following the stabbing of Mongrel Mob Aotearoa president James Stevenson at the Otago Corrections Facility on March 7, 2009. He was attacked by two senior Black Power members armed with prison-made weapons, who stabbed and punched him.
