Guards at New York City’s Rikers Island jail complex reported more use of force against inmates in 2014 than ever before — an average of 11 incidents a day ranging from pepper spraying to throwing punches — amid heightened scrutiny from federal prosecutors to clean up what they call a "deep-seated culture of violence" (PDF).

Figures obtained Wednesday by The Associated Press through a public records request show that correction officers reported using force 4,074 times last year, including 406 incidents in September alone, the month after a scathing federal report said Rikers Island guards resorted to force too often against teenage inmates.

The data also showed that use-of-force rates have increased steadily in the past eight years even as the complex’s overall inmate population has declined. Guards reported 3,285 use-of-force incidents in 2013 when the inmate population averaged 11,687. There were 1,299 reports in 2006 when there were nearly 14,000 inmates.

The news comes on the same day that federal prosecutors, who have since sued to speed up the pace of reforms at Rikers, begin three days of negotiations with city lawyers and correction officials over specific language on use-of-force policy, investigations and other jail problems.

New York City Mayor Bill de Blasio has vowed to reform Rikers Island, America's second-largest jail system, which has come under intense scrutiny since the deaths of two inmates suffering from serious mental illness in recent years. De Blasio has dubbed the jails "de facto mental health facilities." He plans reforms aimed largely at inmates with mental-health or substance-abuse problems who repeatedly end up in prison on minor offenses because there is nowhere else for them to go.

Federal prosecutors declined to comment on the data. A jail spokesman said in a statement that city Correction Commissioner Joseph Ponte has a zero tolerance for excessive force and is updating the department's use-of-force policy, improving staff training, expanding the investigation division and installing security cameras. He said those efforts and others will likely result in fewer incidents in the coming months.

Officers are required to complete use-of-force forms every time there's a confrontation with an inmate, including when they are separating two or more inmates fighting each other. The data obtained by AP include the entire range of incidents from minor to serious use of force, but don't describe what happened in each case.

Norman Seabrook, who heads the powerful Correction Officers' Benevolent Association, a 9,000-member union, said the rise in reported incidents was likely due to guards documenting more often than they did previously in an effort to cover themselves from potential lawsuits and discipline, even if they're legitimately defending themselves from attacks.

But inmate advocates and others point to the scathing August review by federal prosecutors that described a "deep-seated culture of violence" at Rikers, finding that guards regularly used physical force against 16- 17- and 18-year-old inmates, often for perceived slights and signs of disrespect. The report said that behavior likely held true in all of the island’s 10 facilities.

Plaintiffs’ attorneys and others have long argued that the prison complex is consumed by violence. Based on a health department study, AP reported last year that a third of inmates who said their visible injury resulted from a confrontation with prison guards suffered a blow to the head.

In an apparent effort to appease critics, New York City’s jail oversight board on Tuesday voted unanimously to create restrictive housing units at Rikers Island for violent inmates in order to limit guards' longstanding practice of placing inmates in solitary confinement for breaking jailhouse rules and to ban 23-hour confinement altogether for inmates younger than 21 by next year.

The new housing units would lock selected inmates in their cells for a maximum of 17 hours a day, limit their access to religious services and the law library, screen their mail, restrict their movements and deny them certain visits.

Also, under the new rules, 16- and 17-year-old inmates, as well as inmates aged 18 to 21 with serious mental illnesses or physical disabilities, are banned from both solitary confinement and the enhanced security housing. A clinician from the Department of Health and Mental Hygiene can decide if an inmate in either unit should be removed. By next January, inmates ages 18 to 21 will be banned from both housing units, provided correction officials have secured enough funding for therapy, programming and staff to reduce idle time.

The rules also shorten solitary stints to 30 days at any given time, down from 90, with no more than two 30-day stints allowed in any six-month period. It also eliminates so-called owed time in solitary for inmates who didn't complete solitary stints from previous incarcerations and are sent to 23-hour confinement when newly admitted to make up for the time not served.

Jail officials urged the Board of Correction to approve the new housing for what they say are the small number of inmates responsible for a disproportionate amount of jail stabbings and slashings. But inmate advocates and others say the $14.8 million housing initiative is unduly harsh, will deprive inmates of their rights and could fuel further violence.

Dr. Bobby Cohen, a board member, said the initiative was ill-conceived and didn't adequately address root causes of violence on Rikers, including the role that corrections officers play.

Al Jazeera and the Associated Press