The US Department of Justice on Thursday sued telecom major AT&T for alleged misuse of funds in a government program to provide telephone communications for people with hearing impairments.

"Taxpayers must not bear the cost of abuses of the Telecommunications Relay system," U.S. Attorney for the Western District of Pennsylvania David Hickton said in a statement. "Those who misuse funds intended to benefit the hearing- and speech-impaired must be held accountable."

The service is free to users, but telephone companies are compensated approximately $1.30 per minute for providing online intermediaries.

Officials say AT&T, fearing that the loss of the revenue, knowingly allowed ineligible people to use the system, then billed the government for "millions of dollars." To reduce fraud, companies are required to verify users, but the lawsuit accuses AT&T of failing to do so.

AT&T said that it was following Federal Communications Commission rules and isn''t responsible for abuse of the system.

"As the FCC is aware, it is always possible for an individual to misuse IP Relay services, just as someone can misuse the postal system or an email account, but FCC rules require that we complete all calls by customers who identify themselves as disabled," AT&T spokesman Marty Richter said in a statement.