Customers trying to use online bill payment services through CheckFree.com Wednesday were deterred by a power outage that knocked the service off-line for much of the day.

Judy DeRango Wicks, a spokeswoman for Norcross, Ga.-based CheckFree Corp., Thursday confirmed the service was unavailable starting at 4 a.m. and all service was restored by about 6 p.m.

"We had sort of a power interruption" of an unknown cause affecting the company"s facilities, Wicks said. A system of backup power generators came on automatically after the outage. "But then as we were resuming normal power production [later], without the backup, we continued to have problems."

Technicians then turned off the power so they could identify and repair the problems, she said.

Power was restored later in the morning, she said, and CheckFree began restoring Web services for customers by midafternoon.

Checkfree.com is an online bill payment service for about 1,600 banks, credit unions, portals, retailers and brokerage firms. It allows customers to make guaranteed payments online.

Wicks said that all bill payments that were scheduled before the outage were paid Wednesday for customers, and that any customers who were charged late fees by their banks or other vendors as a result of the incident would be reimbursed.

The company maintains one data center for its operations, she said, but it has emergency plans in place that worked as designed during the incident.