BOSTON — More than 900 convicted sex offenders were never classified by the state public-safety agency that monitors offenders after their release from prison and the state lacked addresses of nearly 1,800 sex offenders, preventing their whereabouts from being known by members of the community, according to a new audit.

Auditor Suzanne Bump released an audit Wednesday of the Sex Offender Registry Board detailing how the agency failed to make use of data sharing arrangements between other state agencies, such as the Department of Revenue and the Department of Transitional Assistance, to keep track of sex offenders.

The audit found that between July 1, 2015 and June 30, 2016 the Sex Offender Registry Board failed to classify 936 sex offenders. Classifications are used to measure the threat to the public of reoffending and govern the release of information on convicted offenders to the public.

Of the 936 unclassified offenders, 237 had been convicted of indecent assault on a person over 14, 177 of indecent assault on a child under 14, 143 for rape and 129 for rape of a child by force.

The SORB also lacked current addresses for 1,769 sex offenders.

“When government commits to the taxpayers that it will provide a certain level of safety — and transparency — it has an obligation to do everything within its authority to meet that obligation. As technology and data collection continue to change and improve, our state agencies have an opportunity to utilize that change to break down the silos that have historically existed in government,” Bump said in a statement.

The Sex Offender Registry Board is required to assign convicted sex offenders a classification on a scale of one to three based on their risk of reoffending. The public can request and obtain information on Level 2 and Level 3 sex offenders living in their communities from local police stations.

In a response to the audit’s findings, the SORB said the agency often lacks the legal standing to proceed with classification because it cannot make “requisite notice” to the offenders who fail to register with the board. Of the 936 unclassified sex offenders, the board said it was never able to establish notice for 842. A similar problem exists with recording up-to-date addresses for sex offenders who fail, in violation of the law, to register with the board, and SORB must rely on local law enforcement to track them down.

The board also said it believes 170 unclassified sex offenders are living in another state or country, 100 have been or are believed to be deported and 50 are deceased.

Bump reported that the SORB was not verifying sex offender addresses during the audit period through available databases with the Department of Revenue and Department of Transitional Assistance, and auditors found 39 sex offenders in violation of registration requirements who were collecting public benefits at their addresses through DTA.

SORB, according to Bump’s office, has agreed to utilize information-sharing agreements with DOR and DTA moving forward and to seek other agreements with different state agencies.

At the time of the audit, the SORB registry held records for 21,808 convicted sex offenders, of which 13,127 were living in Massachusetts communities.