AUGUSTA — The Planning Board approved plans for a new, secure 21-bed rehabilitation facility next to the Riverview Psychiatric Center to treat patients who have committed crimes despite concerns about the security of the building and safety of nearby neighborhoods.

Board members approved the new building in a 5-0 vote after adding a condition that all entrances and exits at the facility have at least two locked doors to prevent patients from escaping.

Board member A. Delaine Nye said she was also concerned about whether the building will have adequate staffing, citing reports of patient attacks on staff at Riverview.

“I have concerns about security. All of us have been reading in the paper for a long time about the staffing issues at Riverview, not having adequate staff to manage patients there,” she said.

Last month board members voted to table the proposal after a representative of the state refused to answer many of their questions about it.

The board had tabled the proposal until Tuesday and asked the applicant to come with state Department of Health and Human Services staff who could answer questions about the facility.

State Department of Health and Human Services Commissioner Mary Mayhew, as well as Dr. Ann LeBlanc, director of the State Forensic Service, and other state officials attended Tuesday.

Mayhew said the state shares Nye’s concerns about security and the building would be built and staffed adequately.

She did not estimate the number of staff who would be working at any given time.

“We have a vested interest in this model succeeding, and the only way it will succeed is … if we can ensure the highest level of security for the facility,” Mayhew said. “It is absolutely critical to the department to have an appropriate level of staffing.”

She said security would be in line with security at Riverview.

Board member Peter Pare noted that the board was limited in what aspects of the proposal it can review because a group home is a permitted use in that zone. He said the city would have to rely, in part, on state licensing requirements for group homes to help ensure the facility will be safe.

Board members and advocates for people with mental illness said last month that they were concerned the state’s proposal sounded more like a correctional facility than a hospital.

Mayhew said Tuesday it is neither. Instead, she said, it will be licensed as a residential care facility which, under the city’s zoning ordinance, would be defined as a group home.

The proposal is part of a state Department of Health and Human Services effort to regain federal certification for Riverview and the $20 million annual federal funding reimbursement that comes with it.

The federal agency that oversees Riverview funding revoked the hospital’s certification about two years ago after regulators found many problems during an audit, including the use of stun guns, pepper spray and handcuffs on patients, improper record-keeping, medication errors and failure to report progress made by patients.

Mayhew said creating a new, separate treatment facility for mentally ill patients who have committed crimes is essential for the state hospital to regain that certification.