The government has threatened to override the body advising judges in England and Wales in a row over how ethnic minority offenders should be sentenced, days before new rules are set to take effect.

It comes after the Sentencing Council refused a request from the justice secretary for it to rethink new instructions for judges due to begin on Tuesday.

Under the rules, judges will be expected to consider the lives of offenders from ethnic minority and other backgrounds before deciding on punishment.

The guidelines have prompted a “two-tier” justice row, with critics arguing certain groups of people will be less likely to go to prison for a crime.

Justice Secretary Shabana Mahmood said the guidelines would lead to “differential treatment” of offenders by courts.

Downing Street said Sir Keir Starmer was “disappointed” the council had refused to change the guidance and “all options” were being considered in response, including passing legislation to block the changes.

But shadow justice secretary Robert Jenrick, a vocal opponent of the new guidance, said the threat to legislate was “too little too late”.

“From Tuesday, [Mahmood] will preside over a sentencing system she conceded is two-tier,” he added.

The row began earlier this month when the council, which advises judges and magistrates on prison terms and community punishments, issued new guidance on when a court should order a pre-sentence report into an offender’s life.

These reports contain information about an offender’s background and are intended to help judges decide what sort of punishment is appropriate.

The updated guidance says judges should normally request a pre-sentence report on offenders from an ethnic, cultural or faith minority, and other groups such as young adults under 25, women and pregnant women.

The council argues its new guidance is intended to remedy a “disparity in sentence outcomes” between white and non-white offenders.

But after the Conservatives argued it would lead to a “two-tier” approach to sentencing, Mahmood said she would request it was changed.

She also echoed that “there will never be a two-tier sentencing approach under my watch”.

In correspondence published on Friday, council chair Lord Justice Davis said the council has decided the guidelines “did not require revision”.

He added the guidelines had been subject to a four-month consultation under the previous Conservative government and the “overall response to the consultation was positive”.

He said the council saw no reason to re-run the consultation, although it would now include “clarification” on the language in the guidelines to “correct the widespread misunderstanding which has emerged in the last few weeks”.

An “explanatory statement” would also be added to the council’s website, he added.

He added that although it was not for judges to introduce “overarching policies to redress the imbalance” in sentences, they must “do all that they can to avoid a difference in outcome based on ethnicity”.

“The judge will be better equipped to do that if they have as much information as possible about the offender.

“The cohort of ethnic, cultural and faith minority groups may be a cohort about which judges and magistrates are less well informed.”