Melbourne will again come to a standstill on Friday afternoon, as protesters rallying against the closure of Aboriginal communities across the country stage another sit-in.

With up to 10,000 protesters expected to turn out to the intersection of Flinders and Swanston Streets from 3pm, Victoria Police have told commuters to brace for heavy traffic and public transport delays on Swanston, Elizabeth and Bourke Streets.

Protesters march through the streets of the Melbourne CBD on May 1. Credit:Scott Barbour

Lord Mayor Robert Doyle, who has previously labelled the peaceful protests "self-indulgent", criticising it for causing major disruption in the city, said he now had "sympathy" for the movement.

"I have sympathy for the cause but I don't think this is the right way, or the smart way, to go about raising awareness and engendering support," he said.