Close Nauru and Manus: 100,000 petitioners

More than 100,000 Australians have signed a petition demanding the federal government close immigration detention centres on Nauru and Manus Island in Papua New Guinea.

Lobby group GetUp! delivered the petition to politicians at Parliament House in Canberra on Thursday as the Senate prepared to debate an overhaul of immigration laws, including the return of temporary protection visas for refugees.

Nicole Judge, a former Manus Island centre worker, said asylum seekers suffered institutionalised abuse at the centres set up to process people who had tried to reach Australia by boat.

She accused politicians of justifying cruelty by focussing on deaths at sea at the expense of asylum seekers in detention.

Independent MP Andrew Wilkie said the conditions asylum seekers faced in detention centres were shameful.

GetUp! spokeswoman Erin McCallum said long-term detention caused significant mental health issues for asylum seekers.

"It's time to shut them down and rebuild our country's dignity on the world stage," she told reporters.