An internal Oakland police audit found that officers failed to report using force against a suspect in more than one-third of instances studied in 2018, and all of those unreported incidents involved a non-white suspect.

The audit, completed by the department’s Office of Inspector General and released this week, expands on previous internal and external reports that found that the departments’ celebrated decline in use-of-force incidents was likely exaggerated.

Auditors reviewed 47 incidents where officers had a high probability of using force, including firearm-related crimes and an assault on an officer. After reviewing body camera footage, auditors found 17 instances in which use of force went unreported, the audit states.

Those 17 incidents involved a total of 24 subjects, 21 of whom were black and three of whom were Hispanic.

“It’s a big deal,” said Jim Chanin, a plaintiffs’ attorney in a police corruption case that has prompted 16 years of federal court oversight. “It raises the question of whether there are similar encounters where … they don’t use (force) on white people.”

Chanin said he plans to call for a review on the issue, as well as findings that just four squads out of about 50 accounted for a majority of the unreported incidents.

In a response to the audit, Police Chief Anne Kirkpatrick acknowledged that the report “identified shortcomings.” She vowed to follow the auditors’ recommendations, including reinforcing policies, providing additional training and incorporating technology that tracks when officers unholster or fire their weapons.

“The Department is committed to introspection and is willing to accept and correct our shortcomings in reporting force,” Kirkpatrick said. “Introspection leads to better policing and aligns our practices to our values.”

The report provided further detail on unreported force that didn’t involve pointing a firearm, which was the thrust of previous audits. Auditors found unreported incidents such as officers forcefully pushing a suspect to the ground, lifting a handcuffed suspect off the ground and causing both to fall onto a glass table, grabbing a suspect by the hair, and a forearm strike.

However, the auditors found that none of the reviewed uses of force appeared to be unwarranted.

The Office of Inspector General is tasked with ensuring the Police Department’s compliance in a negotiated settlement agreement following the Riders scandal, in which a group of officers in West Oakland were accused of beating residents and planting evidence.

This week’s audit follows similar reviews released last year, which were conducted by both the Office of Inspector General and the department’s independent monitor. The reports found that officers pointed their guns at people or used other types of force without reporting the incidents as required. Those findings called into question the department’s claim that uses of force fell 75 percent between 2012 and 2017.

City officials said at the time the under-reporting seemed to be based mostly on police officers’ “genuine confusion” about reporting requirements.

The department has since clarified its policy and retrained officers about when to report force, officials said.

The recent audit provides greater detail than previous reviews, and it also offers a first look at use-of-force reporting after the retraining in 2019. Auditors found a near-300 percent increase in reported uses of force by officers, suggesting a “change in practice.”

Megan Cassidy is a San Francisco Chronicle staff writer. Email: megan.cassidy@sfchronicle.com Twitter: @meganrcassidy