VICTORIA Police and Melbourne City Council have cited conflicting legal explanations for last week's eviction of protesters from the City Square, increasing the likelihood of a challenge.

Police Minister Peter Ryan's office referred The Age to Section 6 of the Summary Offences Act outlining controversial ''move-on'' powers created in 2009 to help police deal with alcohol-fuelled violence.

Occupy Melbourne protestors are removed by police at Melbourne's City Square. Credit:Luis Enrique Ascui

But the act specifically excludes the use of the powers on people ''demonstrating or protesting''.

Melbourne City Council pointed to a local law preventing camping in a public place - but it only prohibits tents and infrastructure, not people.