A parliamentary committee has received more than 5700 submissions against a controversial bill introduced by Immigration Minister Scott Morrison that could allow Australia to neglect its human rights obligations under international law if passed by the Senate.

The United Nations High Commissioner for Refugees and human rights lawyers including David Manne have written submissions. They will also appear at a hearing into the suggested legislation on Friday in Canberra.

The key issues against the bill include removing international legal accountability; fast-tracking refugee assessments that do not allow any right of appeal; and removing references to the Refugee Convention in Australian law. There were 5712 submissions to the legal and constitutional affairs legislation committee. The majority were against the changes.

The UNHCR said it was particularly concerned about a decision to “fundamentally alter” Australia’s obligations to refugees assumed by Australia on its signing of the 1951 convention relating to the status of refugees.

Greens senator Sarah Hanson-Young said the bill was “radically cruel”.

“This bill is an affront to Australian decency and compassion,” she said.

Mr Morrison has maintained that the proposed changes will enable the government to stop the boats, and resolve the “legacy caseload” of 30,000 asylum seekers who arrived under the Labor government.

This month, the government’s human rights committee, chaired by Liberal senator Dean Smith, found the proposed changes were incompatible with Australia’s human rights obligations.

The report, delivered by the joint parliamentary committee on human rights, was scathing of nearly all of the government’s proposed changes to the act, saying they would put Australia at odds with international human rights law.

It was particularly critical of a proposal to cut the time in which asylum seekers’ refugee claims would be assessed, warning it could lead to genuine refugees being sent home to face persecution or torture.