LINCOLN, Neb. — Nebraska’s understaffed prison system is still struggling to fill security jobs and won’t be able to address the problem until wages are increased, the state corrections director said Wednesday.

Director Scott Frakes said the worker shortage has contributed to high levels of staff turnover and prevented prison officials from offering more treatment and rehabilitation programs, which have been shown to reduce violence.

“We won’t see significant improvement until we address the pay issues,” Frakes said under questioning from a legislative oversight committee.

His comments came as the Department of Correctional Services announced plans to send a compensation proposal Thursday to the union that represents prison workers. The union has argued that state law requires it to bargain for all “protective service employees,” including those in state psychiatric hospitals and youth centers, and not just prison workers.

It also follows an assault on nine prison workers last week at the Lincoln Correctional Center. Frakes rejected suggestions that staffing shortages played a role in the attack, although some lawmakers have said that the high turnover rate is leading to increased fatigue and burnout among employees.

Staffing shortages, mandatory overtime and inexperienced staff members have been cited as factors contributing to a dangerous work environment in the prisons. Prison employees and their union have said those conditions were partly to blame for a May 2015 prison riot in Tecumseh that left two inmates dead.

A prison staffing report released last week estimated that the department needs to fill 138 positions, at a cost of roughly $653,000 a year. A draft of the report prepared by the department initially called for 254 additional positions, at a cost of nearly $12 million annually.

Frakes said the eliminated positions were not needed, such as officers to monitor front entrances at night, when inmates are kept in their cells. He denied that Gov. Pete Ricketts’ administration pressured him to reduce the number.

“This was a work in progress,” Frakes said when asked about the reduction. “There’s no conspiracy here.”

On top of the recommendations, prison officials have said they need to fill 125 jobs that currently exist but are vacant. The department has roughly 2,300 employees.

Nebraska’s prisons have struggled to keep workers in part because of the state’s low unemployment rate and higher wages paid by county jails. First-year state correctional officers are paid roughly $15.80 an hour, compared to more than $17 and $18 at county jails in Omaha and Lincoln.

Rising insurance premiums have also offset recent wage increases for state prison employees, said former Sen. Steve Lathrop, an attorney for the committee who has overseen previous prison investigations.

Sen. Paul Schumacher of Columbus said addressing the problems will require a long-term increase in spending on prison staffing, but lawmakers won’t have as much money to do so because of income tax cuts approved several years ago under then-Gov. Dave Heineman.

“This wasn’t fate casting some ugly net over us,” Schumacher said. “It was a conscious decision.”

Prison officials note that they’re already taking steps to address staffing problems. A spokesman for Ricketts noted that the governor in 2015 requested funding for an additional 59 positions, which lawmakers approved.

On Wednesday, prison administrators announced plans to award a one-time $500 retention bonus for 1,000 employees in jobs with high turnover and vacancy rates.

In June, the department announced plans to spend $1.5 million on training programs and bonuses using money provided by the Legislature. A recent department survey conducted to reduce turnover found that employees want higher pay, safer work conditions and better communication with top administrators.