HAVERHILL — A local medical equipment supplier has paid $118,524 to settle allegations it overbilled the state for 10 years, the attorney general said.

The company, Home Care Specialists, also must allow reviews of its financial books by an outside auditor for one year, according to a press release from Attorney General Martha Coakley's office.

The company provides oxygen and medical equipment to homes and nursing homes in Haverhill and elsewhere in the Merrimack Valley.

The release said that from 1996 to 2006, the company fused "fraudulent billing practices" to charge Medicaid for pieces of equipment that should have been billed as a single piece of equipment, equipment that was no longer medically necessary, and items and services at higher rates than those approved by MassHealth.

Bill Desmarais, co-owner of the company at 113 Neck Road, said the overbilling was not done on purpose or for profit, and that it was partly the result of a complicated Medicaid reimbursement process. He disagreed with the attorney general's characterization of the overbilling as "fraudulent."

"What we agreed to was that the billing errors were of a technical nature," he said. "There no was intentional deception. It was a mistake."

The company cooperated with the state's investigation and identified some erroneous billing overcharges on its own, the attorney general's release said.

Desmarais said his company paid the money back into the Medicaid fund.

Home Care Specialists is in the city's Ward Hill Business Park.

A Web site for the company says it opened in 1979 and owns a fleet of 18 vans, box trucks and cars that deliver oxygen tanks and other medical supplies to patient homes and nursing homes. The company has about 90 employees, Desmarais said.

The company also offers sleep therapy equipment and consultations from registered nurses and respiratory therapists, the Web site says. Its distribution center is in Dover, N.H.

The case was handled by Assistant Attorney General David Marks and was investigated by agent John Walsh and data analyst Anthony Megathlin in the office's Medicaid fraud division.

Investigators said Home Care Specialists of Haverhill overbilled the state Medicaid program for:

Pieces of equipment that should have been billed as a single piece of equipment

Equipment that was no longer medically necessary

Items and services at higher rates than those approved by MassHealth