The Barangaroo blaze in inner Sydney has sparked calls for an urgent city-wide audit of construction safety standards from the state's peak union body.

Unions NSW secretary Mark Lennon will write to Finance Minister Andrew Constance on Thursday following what he says is the the third major scare on a building site in less than 18 months. The push comes after flames broke out at the Barangaroo construction site on Wednesday afternoon, forcing the…