Two-tier sentencing rules could cost the taxpayer nearly £20million each year, the Tories have warned. It comes as Justice Secretary Shabana Mahmood will aim to urgently introduce targeted legislation “as early as possible” this week to clamp down on issues at the centre of a row.

Earlier this month the Sentencing Council published new principles for courts to follow when imposing community and custodial sentences, including whether to suspend jail time. The updated guidance, which comes into force from Tuesday, says a pre-sentence report (PSR)will usually be necessary before handing out punishment for someone of an ethnic, cultural or faith minority, alongside other groups such as young adults aged 18 to 25, women and pregnant women.

Critics fear the change could discriminate against those who do not fit into these groups.

Shadow Justice SecretaryRobert Jenrick said: “Shabana Mahmood has lost control of the justice system.

“From Tuesday, the taxpayer will be made to foot the bill for tens of millions of pounds for a justice system that is biased against white people and Christians.

“Anything she does now is too little, too late. She should have backed my Bill that would have given her the powers to stop the two-tier sentencing guidelines, but she refused.

“The sacred principle of equality before the law is now being torn to shreds because of her and Two-Tier Keir.”

Ms Mahmood, who staunchly opposes the measures set to come in, warned “all options are on the table” to alter the guidance.

The Sentencing Council refused a request from her to change it.

Modelling by the Tories suggested an additional 28,750 PSRs could be required.

They said this would heap pressure on the already struggling prison system, leading to sentencing delays and growing court backlogs.

In 2022, 62,104 PSRs were prepared by the probation service.

Based on the new guideline, the Tories analysis said approximately 23% of convicted individuals now fall into groups for whom a PSR will be required.

If even half of these individuals previously did not receive a PSR, this would result in an estimated 28,750 additional PSRs annually, equating to a 48% increase in overall volume.

Adjusting for inflation the price per PSR is around £607.

The analysis continued that if these guidelines increase PSRs being issued by that percentage, that means an additional cost of at least £17.5 million.

Meanwhile Lord Falconer, a Labour former justice secretary, warned ministers against making an emergency change to the law in order to overrule the Sentencing Council.

Labour peer Lord Falconer said he agreed with Ms Mahmood the Sentencing Council was wrong, as the new guidance “gives the impression of an unfair system”.

But he cautioned the Government against threatening to change the law in order to bypass the Sentencing Council.

The Justice Secretary needs to hold a consultation into the proposals, Lord Falconer said, instead of relying on work done by the previous government.

In words of caution for Ms Mahmood, he told the BBC: “I wouldn’t be in favour of emergency legislation before the consultation.

“The reason I’d be against emergency legislation at this stage is because I would take the view that the Government would get themselves into a very difficult position if every time they disagreed with the council’s views, they had emergency legislation.”