Police cracking down on anti-mining protests in Melbourne “set a tone of violence from the outset”, according to a scathing report by independent legal observers.

Voluntary observers posted at the picket of October’s International Mining and Resources Conference – Australia’s largest mining event – have detailed a range of concerns about police tactics used to quell the protest.

A 45-page report, co-authored by Anthony Kelly, executive officer of the Flemington and Kensington Legal Community Centre, claims police were unnecessarily aggressive during arrests, made unlawful use of police powers and entered the three days of protest from October 29 to 31 with an “antagonistic” attitude.

Police use pepper spray as protesters attempt to stop conference members entering the mining conference in October. Credit:David Crosling/AAP

The report, seen by The Age ahead of its release on Saturday, documents what observers believe to have been excessive use of capsicum spray, overzealous use of batons and dangerous use of police horses to break up protest lines. More than 100 protesters were arrested over the course of the demonstration.