Police are looking for a man who launched a racist rant at customers and staff at a Centrelink office in Salisbury, in Adelaide's north.

A customer filmed the incident on her mobile phone, and the video has now been viewed more than half a million times on social media.

It shows the man hurling abuse at staff, angry that they're giving money to people from other racial backgrounds, but not him.

"Quick run over there, because the racist person is freaking out," he said.

"I didn't vote for multiculturalism... But you will do whatever you can for every other c--- except for Australians," he said.

Police were alerted after a staff member pressed a duress button (Source Facebook) (9news)

Police have told 9NEWS they were called to the Centrelink building at about 2.10pm on Monday after a staff member pushed a duress button.

Staff can be seen trying to shield children and parents from the man as he yelled threats.

"I'm gonna smash all of youse [sic]," he said.

He then turned his racist abuse to a female customer on the other side of the room.

"How much money are you getting you black b----?" He yelled.