Vic rally against offshore detention

Hundreds of protesters have rallied in Melbourne against Australia's treatment of asylum seekers, calling for an end to offshore processing.

The rally, organised by the Refugee Action Collective, demanded the Manus Island detention centre in Papua New Guinea be closed after a riot led to the death of a 24-year-old Iranian asylum seeker on Monday.

Speaking at the rally in Melbourne's CBD on Friday, Greens deputy leader Adam Bandt said it was wrong for Australia as a developed country with immense wealth to expel people to countries that have problems of their own.

"A young man came to our door seeking our help and we killed him. That is the reality of what has happened under the Abbott government's watch," he said.

"What we have seen over recent days is the twisted logic that lies at the heart of this offshore detention system."

Demonstrators chanted "Lock up Abbott, throw away the key, we won't stop until we free the refugees" as they marched from the State Library to the Department of Immigration and Citizenship building where they staged a sit-in.