The joint committee on human rights, which is tasked with examining bills that come before Federal Parliament, has found that the family payments package, which proposes to cut family tax benefits to single income families, may breach people's right to social security and an adequate standard of living.

The report, which was tabled in Parliament on Tuesday afternoon, comes as the government hit an obstacle in its bid get the family payment changes through the Senate.

Labor announced it would oppose all measures in the bill, apart from one. In a move that will save almost $500 million over four years, Labor will back a cut to family tax benefit part B (paid to single income families) to couple families, once their youngest child turns 13. Currently, they can receive the payment until the child turns 16 or 18 - depending on whether they are still at school.

But the human rights committee had particular concerns with the measure, as well as the government's plan to cut payments to single parent families to $1000 a year once their youngest child reaches 13 - a component of the bill that Labor does not back.

The committee, which is chaired by Liberal MP Philip Ruddock and has five Coalition members out of the 10 members, said the proposal would "limit the right to social security and right to an adequate standard of living".

It adds that government's explanation of how the bill is compatible with human rights "does not sufficiently justify the limitation for the purposes of international human rights law".

The committee notes that the right to social security and an adequate standard of living are protected in the International Covenant on Economic, Social and Cultural Rights, which Australia ratified in 1975.

"Family tax payments are an integral part of Australia's social welfare scheme and critical for many families to provide an adequate standard of living," the report says.

As a result, the committee has asked Social Services Minister Christian Porter for more advice about the bill and whether the proposed change is a "proportionate measure".

The committee also takes similar issue with the plan to strip the 1.7 million families who receive family tax benefits of end-of-year supplements, which would save the budget $4 billion over four years.

A spokesman for Mr Porter said the family payments bill was "carefully targeted to assist those most in need of assistance".

"It makes sensible savings, which are reinvested into family tax benefit part A and the government's $3.5 billion Jobs for Families [childcare] package.

"We want to ensure that those Australians who have the capacity to work have the opportunity to work."

Dissent over same-sex marriage bill

The human rights committee report also contains a dissenting report on the cross-party bill to legalise same-sex marriage, sponsored by Coalition MP Warren Entsch and Labor's Terri Butler.

While the main report finds that the bill promotes equality and non-discrimination and is divided on whether it limits the right to freedom of religion (as it does not allow civil celebrants to refuse to marry same-sex couples on the basis of religious belief), a dissenting report from three Coalition MPs argued the committee had made "a number of unsupported findings".

Senator Matthew Canavan and MPs David Gillespie and Michael Sukkar argue that the bill is not compatible with several human rights, including the right to freedom of religion and the right to respect for the family. It also finds that it limits the rights of the child.

This dissenting report comes after several countries, including Ireland and the Netherlands, recommended Australia allowed same-sex marriage, during the United Nations' review this week of Australia's human rights record.

Greens spokesman on marriage equality Robert Simms accused the Coalition dissenters of "cloaking bigotry and homophobia in the language of human rights".

"It is deeply insulting to LGBTI Australians and their families and friends to suggest that same-sex parents are somehow deficient."

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