Twenty portraits, plaques, and sculptures the Massachusetts State House acquired for its art collection since 2001 were improperly appraised or recorded, the state auditor’s office has found.

The works, including portraits of former governors and memorials to police officers and firefighters, are overseen by the Bureau of the State House, the agency responsible for maintaining and restoring the building.

The auditor’s office found that the bureau failed to document the valuables as state policies require. But state officials Thursday said the artwork, among 300 pieces in the State House’s permanent art collection, was all accounted for.

The State House bureau told the auditor’s office it conducted visual inspections twice per year, but did not provide documentation. The bureau said it will work with the state comptroller’s office to register the 20 pieces in a database, and will correctly record much of the artwork it has acquired over the past 15 years.

“The State House is not only the seat of our state government, but a place where the history of the Commonwealth comes alive,’’ state Auditor Suzanne Bump said in a statement.

She pledged to help the State House bureau “identify proper protection and documentation of the artwork that lines the halls of this historic building.’’

The audit also found that the bureau’s computer equipment was not properly inspected by its overseeing agency, the Executive Office of Administration and Finance. That office said it failed to review the equipment because of time and budget limitations, the audit found.

The findings came after the State House bureau provided inaccurate or undocumented answers to a questionnaire from the auditor’s office.

Mike Wessler, a spokesman for the auditor’s office, said auditors will reconvene with the State House bureau in six months, to make sure it has complied with the audit’s directives.

Astead W. Herndon can be reached at astead.herndon @globe.com.