EIGHT protesters will be charged after they refused to let authorities move asylum seekers from the Villawood Detention Centre in Sydney.

About 30 protesters began blocking the gates into the centre about 4.30am (AEDT) on Thursday, stopping buses from moving asylum seekers to the remote Curtin Island Detention Centre in Western Australia.

Protester Clo Schofield said the protest had been peaceful until a portion of the group refused to comply as buses full of asylum seekers tried to leave the centre.

"People refused to move away from the road, interrupting the buses, not allowing them to leave," she told AAP.

"Towards the end, things got very violent."

The buses left the area shortly after the arrests, she said.

Police said eight people were in the process of being charged at Bankstown police station for failing to comply with a police direction.

Some of the 83 asylum seekers being moved from the centre are taking legal action against the federal government over the alleged leaking of personal details.

They are due to have their case mentioned in court on Friday.

Michaela Byers, the lawyer for the 16 detainees involved in the legal action, had speculated the proposed move was designed to make the detainees lose hope and return to their homelands voluntarily.

Of 16 detainees involved in Friday's legal matter, three were removed on Thursday.

The protesters said that up to 50 asylum seekers have begun a sit-in protest inside the detention centre.

Greens Senator Sarah Hanson-Young says the protesters were doing what the government should have been doing.

"Which is helping to protect the refugees and to ensure they have proper legal assistance," she told AAP.

Last week, the government announced it would cut free legal assistance for asylum seekers, a move Ms Hanson Young called cruel and unjust.