HARRISBURG , Pa., May 16 (UPI) -- Federal nuclear regulators said they will be conducting inspections at Pennsylvania's Three Mile Island Nuclear Generating Station after a security lapse.

The U.S. Nuclear Regulatory Commission said the security issue, which occurred last summer, was discovered and reported by the operator of the plant, AmerGen Energy, The Patriot-News in Harrisburg, Pa., reported Friday.

The commission didn't specify the nature of the security lapse, only that it didn't involve inattentive or sleeping security officers and was of moderate to serious significance.

AmerGen Energy officials said the issue was immediately corrected.

A Nuclear Regulatory Commission spokesman said close inspections of security operations at the plant will be conducted during the next 12 months.