Canberra, Nov 9 (IANS): Five activists on Thursday scaled the Sydney Opera House to protest against Australia's treatment of refugees on Manus Island in Papua New Guinea (PNG).

The Whisteblower Activist and Citizens Alliance (WACA) said the climb began at 10.30 a.m. to highlight "the inhumane treatment on Manus Island of men seeking asylum".

Activists managed to climb the icon despite a recent security upgrade designed to bring the venue up to international standards, ABC News Australia reported.

The Manus Island Regional Processing Centre -- used to screen people seeking asylum in Australia -- officially closed on October 31. However, about 600 refugees are refusing to leave, citing fears for their safety in the local community.

Australia shut down the centre after a PNG court ruled it was unconstitutional, urging asylum seekers to move to transit centres elsewhere on the island.

The five activists, two men and three women, were arrested after trying to unfurl signs calling for the refugees to be evacuated. Police prevented the protesters from displaying a large banner. Smaller placards read "evacuate Manus" and "Australia: world leaders in cruelty #BringThemHere".

The activists were taken to a police station and charged with trespass. No one was injured. They were granted conditional bail.

In a video posted to the social media, one of the protesters on top of the Opera House called on the Turnbull government and Labour Party to evacuate Manus Island and bring the refugees to Australia.