Louisiana's Medicaid program improperly paid $4.2 million over a five-year period for laboratory services and tests that shouldn't have been covered, according to an audit released Monday.

Legislative Auditor Daryl Purpera's office reviewed payments between July 2011 and June 2016, mainly during former Gov. Bobby Jindal's administration.

The auditors said the $4.2 million was paid by the health department and private managed-care companies who administer health plans for many of Louisiana's Medicaid recipients. They said the payments from the state-federal health insurance program were sent to labs that weren't properly certified for the tests or for claims that had invalid procedure codes.

The department didn't monitor the managed-care companies to ensure their lab payments were in compliance with their state contracts, auditors wrote.

"Considering rising state health care costs and limited budgets, it is important that (the health department) ensure that Medicaid dollars are spent appropriately," Thomas Cole, first assistant legislative auditor, wrote in a letter to lawmakers with the audit.

The health department said that since Gov. John Bel Edwards' administration took office in January 2016, it has started an automatic monitoring system for the lab payments and more regularly reviews its payment process.

"When this administration came on board, we discovered that in spite of Medicaid policy, some labs that were being used by clinics, nursing homes, hospitals and other providers did not have the proper certifications," Jen Steele, Medicaid director for the health department, said in a statement.

The department disagreed, however, that $1.7 million was improperly paid for claims with an invalid procedure code, saying the code at issue was valid at the time of the spending.