PHOENIX (AP) — A review by Arizona child welfare officials of a second batch of ignored child abuse and neglect reports has found 1,800 additional cases that were serious enough to warrant a full investigation, The Associated Press has learned.

Child Protective Services has been under fire since officials revealed last month that 6,500 complaints of abuse and neglect made to a hotline were ignored since 2009. The agency responded by re-examining the cases and breaking down the investigation into two parts: the 3,600 calls to the hotline from 2009 to December 2012 and the roughly 3,000 that occurred in 2013.

The agency previously disclosed that it found about 1,800 cases in the 2013 period that require a full investigative follow-up — and 10 demanding an urgent response. The AP obtained the results of the 2009 to 2012 cases, and the findings showed another 1,800 requiring a full investigation. Four required an urgent response.

The review was completed by the state's Child Protective Services department last Monday. The agency at first declined to release the results, but produced the information late Friday after the AP filed a public records request.

A full CPS investigation usually entails a case worker speaking with the child and their siblings and making a home visit. The case worker then completes an assessment and may remove the child, offer family support services or close the case, according to the agency's website.

The disclosure of the ignored cases last month by Department of Economic Security Director Clarence Carter has brought added attention to the state's overburdened child welfare system. An angry Gov. Jan Brewer last week declared the problem intolerable and said the people responsible would be held accountable. She defended Carter, whose department oversees Child Protective Services.

A new team appointed by Brewer plans to do its own review of the cases. The team is headed by the leader of the state's juvenile corrections department, Charles Flanagan. He cast doubt on the accuracy of the agency's review of the cases, saying some CPS workers involved in the follow-up were involved in the initial complaints.

Brewer's "Child Advocate Response Examination," or CARE team, expects to complete its initial review this week. An update posted late Friday on the team's website contained some discrepancies between its review and the CPS review. For instance, CPS reported that 329 of the children identified in the ignored abuse and neglect reports were the subject of subsequent open cases. The CARE team listed 1,403 that had subsequent abuse or neglect reports. The new group also said it found 22 additional cases requiring "eyes on the child." The CPs review found just 14.

Five senior CPS workers were placed on administrative leave last week as their role in the decision to close the cases is investigated. The agency has declined to identify them.

Besides the new CARE team, Brewer has assigned state police to investigate who was responsible for deciding to close the cases, which require investigation under state law.

The practice of labeling some cases phoned into a child welfare hotline as not worthy of investigation was initiated in late 2009, as a budget crunch hit the agency and it sought ways to close cases early and avoid adding to its staff's already-overburdened workload, Carter said in November. It was briefly revived the following year. In 2012, a new team of senior CPS supervisors and managers revived it again, closing thousands of cases before the practice was halted last month.

The agency's troubles have brought criticism from Republicans and Democrats. House minority leader Chad Campbell, D-Phoenix, has called for Carter's resignations and a complete overhaul of CPS.

"At this point, I'm just so skeptical of everything over there," he said Monday.

Maricopa County Attorney Bill Montgomery, a Republican, has said it's too soon for Carter to be ousted, but has mentioned making CPS a separate agency as one way to end what appears to be systemic problems.

EDITOR'S NOTE: This story has been modified to reflect the full version of the Associated Press story from Dec. 9, 2013. The 1,800 cases newly identified as serious enough to warrant a full investigation were a subset of, not in addition to, the original 6,554 complaints of abuse and neglect that had been ignored by Arizona Child Protective Services.

Updated 12/9/2013 at 11:01 a.m.