Media playback is unsupported on your device Media caption Home Secretary Theresa May: "This is a matter of great concern"

Police are urgently reviewing the cases of thousands of suspects after a court ruling restricted their powers to bail them for further questioning.

The ruling - in a case involving Greater Manchester Police - means that suspects can be released on police bail for no more than 96 hours (four days).

At present, suspects can be released on bail pending further inquiries for weeks, or even months, in some cases.

Home Secretary Theresa May said it was a matter of "great concern".

The fresh guidance to police custody officers in England and Wales followed a ruling in the Hookway case by Mr Justice McCombe in the High Court in May.

It says officers will have to re-arrest suspects in order to detain or question them again, but only if they have "new evidence".

Guidance from Scotland Yard says that police will also no longer have the power to detain a suspect who breaches their bail conditions or fails to surrender.

'Verge of disaster'

It is understood the home secretary was informed of the judgement and its possible implications on Friday.

Mrs May said the Home Office was considering whether to appeal against the ruling or introduce emergency legislation.

She said: "We're working with Acpo at the moment and looking at a number of possibilities as to how we can advise the police on this issue.

"We are conscious of the concerns this judgment has brought in terms of operational policing."

Analysis For over 25 years, since the Police and Criminal Evidence Act, it's been customary for officers to release suspects on police bail while they complete their investigations. Sometimes this can take weeks or months. When the suspect returns to the police station, he or she might be detained for further questioning, re-bailed pending additional inquiries, charged or released without action. The ruling in the Hookway case has thrown this long-established practice into disarray. On the face of it, it means police have four days at most to bring charges - regardless of whether suspects are in custody or not. The reality is that in thousands of cases this won't be possible. Police, under the new interpretation of the laws, will be powerless to prevent suspects walking away from a police station, with no conditions attached, unless they can find new evidence to arrest them again. No wonder the Home Office and senior officers are urgently seeking a remedy.

Shadow home secretary Yvette Cooper said it was "a matter of grave concern".

"Because it seems this has immediate effect, it will disrupt vital ongoing investigations and hugely hamper the police in their job," she said.

"Police officers I have spoken to are deeply alarmed at the implications for criminal cases they are working on right now."

West Yorkshire Police said it has 4,260 suspects on police bail.

The force's Chief Constable Norman Bettison said the ruling meant suspects would have to be charged or released without further action once 96 hours had elapsed.

It now has no provision to carry out further inquiries with suspects on bail.

He said: "It's on the verge of a disaster now because the question being asked by my custody sergeants is, 'What do we do, boss?'

"I cannot countenance turning people away from the charge office and telling them all bets are off and they are free to go."

He added: "We are running round like headless chickens this morning wondering what this means to the nature of justice.

"My holding position with my officers is that I can't believe this is what was envisioned."

He has told his officers to continue working to their usual guidelines until further advice is issued.

The BBC's home affairs correspondent Danny Shaw said one senior police figure had described the implications as "dire" as it would have far-reaching effects on serious and complex cases where police needed time to gather evidence and speak to witnesses, such as in rape allegations.

'Chaos and concern'

Association of Chief Police Officers (Acpo) lead spokesman on the issue, Essex Chief Constable Jim Barker-McCardle, said the ruling had a "profound impact" on the way police investigate crime.

He said: "Unless overturned, the indications are its effect is that police can no longer put anyone out on bail for more than 96 hours without either being in a position to charge or release."

And he told BBC Radio 4's the World at One the ruling had "thrown the whole of policing into the air".

"There's chaos and concern out there. We're working hard at the moment with the Home Office and the home secretary and the CPS to make sense of this, and at the moment, sense to me looks like legislation, and potentially emergency legislation," he said.

The ruling was made by the district judge at Salford Magistrates' Court, who said the detention clock continued to run while the suspect was on bail.

The case concerned a murder suspect, Paul Hookway, who was arrested in November. Police had been given permission to detain him for 36 hours but he was released after 28.

Five months later, police applied to the courts to extend the period of detention from 36 hours to the maximum of 96 hours. But the district judge refused, saying that the 96 hours had expired months ago.

Greater Manchester Police sought a judicial review, but the ruling was upheld at the High Court.

After the ruling, the Crown Prosecution Service and Acpo sought expert legal advice which stated that it set new case law and had to be adhered to.

The force is now seeking leave to appeal at the Supreme Court.