Aetna, the insurance giant, plans to reimburse thousands of current and former college students across the country who were underpaid for claims involving health-care providers outside the company’s network, The Hartford Courant reported yesterday.

The company, which is based in Hartford, Conn., discovered and disclosed the problem as the state attorney general was investigating how insurers pay for out-of-network care. Chickering Claims Administrators, which manages Aetna’s student-health insurance business, had “miscalculated a small percentage of its claims,” a spokeswoman for the parent company told the Courant.

Aetna expects to reimburse 1,300 students at seven public and private colleges in Connecticut a total of $100,000 for claims processed in the past 10 years, according to the Courant. The company has yet to announce the number of students affected nationally and the amount that they must be reimbursed, the Courant said.

The state attorney general, Richard Blumenthal, said in a letter to Aetna that he appreciated its disclosure but that he was “deeply concerned about the apparent absence of oversight that allowed the lapse to occur.” —Sara Lipka