IBM denies any wrongdoing
IBM is being investigated by the US Department of Justice over allegations of anti-competitive behaviour, a computer industry trade body has said.
The Computer and Communications Industry Association (CCIA) said the investigation came after it urged officials to look into the matter.
CCIA accuses IBM of withdrawing software licences from business clients who do not also buy its hardware.
IBM denies any wrongdoing and says it will co-operate with any investigation.
The Department of Justice has declined to comment.
The CCIA said the investigation centred on IBM's mainframe operating systems.
The association's spokesman, Ed Black, said the scope of the Justice Department study was "quite broad".
The news comes a week after an anti-competition complaint against IBM by software developer T3 Technologies was thrown out by a judge in Manhattan.
"We understand the Department of Justice has asked T3 for documents from the litigation," said IBM in a statement.
"IBM intends to co-operate with any inquiries from the Department of Justice.
"We continue to believe there is no merit to T3's claims, and that IBM is fully entitled to enforce our intellectual property rights and protect the investments that we have made in our technologies."