By getting her way and allowing police to consider disclosing the ethnicity and nationality of suspects charged in high-profile cases, Yvette Cooper has solved one enormous headache for the criminal justice system. But she may have caused another, which could have consequences for race relations.

The home secretary has encouraged senior police officers to free themselves of longstanding protocols so they can combat the prolific use of social media by far-right bloggers and organisations that have escalated disinformation around high-profile incidents.

Last summer’s national riots were fomented from an early stage by misinformation about the Southport killer – he was claimed, in posts recycled tens of thousands of times, to be a Muslim, foreign-born and an asylum seeker. All three statements turned out to be wrong.

Until today, there was nothing in the College of Policing’s guidance that actually prevented police giving information about the nationality, asylum status or even ethnicity of someone who has been charged.

The police are restricted as to what they can say about suspects. But the guidance on media relations – and what would be released to the public – said that if someone was arrested, police should only give the suspect’s gender and age.

Once a suspect was charged, the guidance said police could give out the suspect’s name, date of birth and address. Before 2012, police forces made decisions on what information to give to the media on a purely case-by-case basis, decisions often made depending on the force’s relationship with individual journalists and media outlets.

But it was Lord Leveson’s damning 2012 report on press ethics that prompted police forces to become more cautious because of concerns that releasing the ethnicity of suspects could be used to feed false narratives.

Leveson examined testimony from the National Union of Journalists claiming that some national newsrooms openly encouraged racist reporting. One reporter was told by the news editor to “write a story about Britain being flooded by asylum-seeking bummers”, another was told to “make stories as rightwing as you can” and another was told to go out and find Muslim women to photograph, with the instruction: “Just fucking do it. Wrap yourself around a group of women in burkas for a photo,” the testimony said.

He examined numerous reports including a Daily Star article under the headline “Asylum seekers eat our donkeys,” which claimed that donkey meat was a speciality in Somalia and eastern Europe and blamed asylum seekers, without any evidence.

Leveson concluded that “when assessed as a whole, the evidence of discriminatory, sensational or unbalanced reporting in relation to ethnic minorities, immigrants and/or asylum seekers, is concerning”.

Fast-forward 12 years to Southport, and Merseyside police were left making decisions on whether to release information on the ethnicity and nationality of the killer of three young girls in order to dispel public anger that had spilled on to the streets. Senior officers had to deal with major criminal incidents and took days to dispel social media untruths.

Such disinformation was at least partly responsible for last summer’s riots. At the time, Merseyside police said they were not giving out more information because of the contempt of court rules.

It is hoped that the new guidance will mean police will no longer be left flat-footed when responding to viral social media posts by extremists. Decisions on releasing such information will remain with police forces, with wider legal and ethical considerations also taken into account, the National Police Chiefs’ Council said, but verifying a suspect’s immigration status is up to the Home Office.

There is concern among some former police and race campaigners that Cooper’s change will undo the restrictions imposed after Leveson and fuel racist sentiments.

The former Met chief superintendent Dal Babu has warned of the “unintended consequences” of the new guidance, which he said could lead to more online speculation in cases where these details are not released.

“The danger is there will be an expectation for police to release information on every single occasion,” he told BBC Radio 4’s Today programme.

The Home Office says it will not be encouraging the release of ethnicity and immigration status in all cases, and there are notable occasions when it has not. But a former race adviser to No 10 said: “Yvette has unwittingly opened a Pandora’s box. After every charge, everyone with a union jack on their X bio will demand from the police the ethnicity of the suspect.

“The Home Office is going to get even more demands for the asylum status of every Black or brown suspect. It is going to be chaos, and has handed Nigel Farage another stick to beat Labour with.”

There could well be a knock-on effect on mainstream reporting and community relations, campaigners believe. Enny Choudhury, from the Joint Council for the Welfare of Immigrants, said: “Releasing the ethnicity of everyone suspected of serious crimes will do nothing to help victims or secure justice – it will simply fuel mistrust, deepen divisions, and make Black and brown communities more vulnerable to prejudice and harm.”