Contentious bail laws in New South Wales which would likely see more children imprisoned will face an internal challenge, with Inner West mayor Darcy Byrne advocating for their repeal.

The laws brought in by the NSW Labor government and described as betraying Aboriginal children, have been criticised by Indigenous and legal groups, as well as Labor groups. They will now face an internal challenge, with Mayor Byrne planning an "urgency motion" at the upcoming Labor conference to have the laws repealed.

He said the laws aimed to incarcerate more children, and he would work with Aboriginal Legal Service (ALS) and other Indigenous groups "in opposition to the draconian laws".

"I will be tabling an urgency motion at the upcoming NSW Labor Conference for these laws, aimed at locking up more children, to be immediately repealed and a sophisticated, evidence-based package of juvenile justice programs to be funded and implemented instead," he said.

"There's been a real outpouring of emotion from Labor Party members and social justice advocates who are shocked and saddened that the NSW Government is willing to incarcerate even more Aboriginal kids."

ALS NSW/ACT chief executive Karly Warner said it was "heartening" to see members within the NSW Labor party understood "what a bad idea this policy is".

"Not only is it a shocking step backwards on Closing the Gap, for safety in regional communities and for children – it's also a bad political call from the Premier who has shown he's listening to media fear campaigns more than communities," Ms Warner said.

"This won't work well for the government on any front."

Mayor Byrne, who was a youth worker with Indigenous children before entering politics, said the laws, designed to address "localised youth crime in some regional communities," would result in children across the state being incarcerated.

He previously spoke out against the legislation when it was announced, arguing party members were furious the government had taken such a hardline approach to children – many of whom are vulnerable and Indigenous.

"There was no consultation conducted and the Government has no mandate for such a reactionary policy," he said.

"Therefore, Labor Party members who believe in overcoming Indigenous injustice have no choice but to bring this fight on to the Conference floor."

The laws passed last week make it harder for teenagers to get bail, as well as criminalising "posting and boasting" about criminal offences on social media. The state government also announced $26.2m worth of funding to combat youth crime in regional NSW.

They were described as a "knee-jerk response" and faced criticism from the crossbench and even fellow Labor MPs but passed without amendment.

Attorney-General Michael Daly flagged the laws would result in more children being incarcerated before they were introduced, arguing, "If there was another option available to us today, to keep these children safe, we'd take it, but there isn't".

Ms Warner labelled them a "short-term political stunt that won't fix a thing on the ground in communities," and argued the legislation was a "line in the sand" moment.

"We cannot accept an Australia that puts children in jail instead of evidence-based policy that actually makes communities safer," Ms Warner said.

On Wednesday, Ms Warner said: "We'll be working to ensure these dangerous policies are overturned and replaced with the evidenced-based policies from Closing the Gap that can actually reduce crime and not ruin children's lives."

Last week, an open letter circulated by NSW Society of Labor Lawyers highlighted the significant division in the party about the legislation.

The letter argued the legislation was a "band-aid solution, likely to lead to the incarceration of particularly vulnerable groups in our society, which will further entrench criminality in regional communities and strain our criminal justice and prison system".

Premier Chris Minns said the laws struck the right balance, and disagreed with accusations the changes were a "betrayal" of young people.

Minns' Labor colleague Cameron Murphy voted for the bill - as is required by a Labor MP when the caucus decides policy - but said he has personal objections to them.

"We in the Labor Party went to the last election on a platform that committed … to closing the gap … This bill, even though designed with the best intentions … will ultimately send more Indigenous kids to jail," he said in parliament.