Police in Greater Manchester have been unable to charge many suspects since the introduction of a new £27m computer system, leading to a massive backlog, lawyers have claimed.

Robert Moussalli, a lawyer specialising in cases involving children and young people, said police had sent suspects home from stations following their arrests because they were unable to charge them due to problems with a new IT system introduced last month.

The Integrated Operating Police Operating System (iOPS) was supposed to make it easy for officers from Greater Manchester police (GMP) to access all police records dating back to 1974 and provide “a single, integrated platform to support public contact, policing response and investigative activity”.

But the system, delivered by the outsourcing company Capita, more than a year behind schedule at a cost of £27m, has been fraught with problems. Officers told the Manchester Evening News, which first reported on the issue, they were unable to do their jobs properly and that IT failures were putting the public as well as the police at risk.

Moussalli, who defends daily at Manchester youth court, said there was a massive backlog of cases as a result of problems with iOPS.

“To start with they had real problems because for some reason the new software wouldn’t let them charge anyone, so they were having to release suspects ‘under investigation’ unless they processed them manually, which takes a long time,” said Moussalli.

If a suspect is released under investigation, they are free to go about their lives as normal and are not subject to any limitations on their freedom as they might be if they are bailed.

Other lawyers confirmed the same issues at police stations.

This week one of Moussalli’s clients, a 16-year-old boy, appeared in Manchester youth court to face charges of assaulting a police officer and possessing a knife. His case was adjourned after a prosecutor apologised to magistrates that she did not have any information about his alleged crimes and could not open the case - police had not been able to upload details to iOPS and send it to her.

Two further cases in the youth court were adjourned for similar reasons blamed on iOPS.

Four teenagers accused of joyriding almost a year ago were sent home from court with apologies after the Crown Prosecution Service (CPS) admitted it hadn’t been able to access their files because of issues with iOPs.

Nicola Durham, the CPS prosecutor, apologised to their mothers, who had taken time off work to attend court. She also asked for an adjournment on Tuesday to a case involving a 17-year old boy accused of drink-driving. She told magistrates she could not open the case because problems with iOPS meant police had not given her background information, including previous convictions, that was necessary for the case to progress.

A spokesman for GMP defended iOPS, saying: “This project is the largest and most complex of its kind in the UK policing sector. As with any major IT transformation project there will be challenges, however, these were anticipated.”

He suggested the problems in Manchester youth court could be down to a “number of factors” and not necessarily the new computer system, despite the prosecutor specifically blaming iOPS in open court.

“We will continue to work closely with the CPS to mitigate any risks and are in daily contact to ensure the administration of justice continues. Protecting the communities we serve will always be our number one priority,” he said.

A spokeswoman for the CPS said: “We have worked closely with Greater Manchester police to mitigate any risks to the delivery of case material as the new police IT system is introduced. We are in daily contact with GMP to ensure there are effective contingency arrangements in place if necessary and we will continue to work closely with them.”

The Greater Manchester branch of the police federation said it was “actively engaged with GMP to resolve the issue” and could not comment further.