The U.S. International Trade Commission (ITC) is investigating the handsets of eight major smartphone vendors as part of a probe into patent infringement allegations.

Singapore-based Creative Technology Ltd. and U.S.-based Creative Labs Inc. have accused Samsung, LG Electronics, Sony, ZTE, Lenovo, Motorola Mobility, HTC and Blackberry of infringing on patents related to “portable electronic devices, such as smart phones, with the capability of playing stored media files selected by a user from a hierarchical display.”

Creative Technology and Creative Labs have requested the commission issue a limited exclusion order and cease and desist orders to the companies in question.

The ITC said it has not yet made a decision on the merits of the case, but will assign it to one of its administrative law judges for an initial hearing. That judge will make a preliminary determination as to whether a patent violation has occurred, and that decision will be reviewed by the commission, the ITC said.

The ITC said it is aiming to make a final decision on the case at the “earliest practicable time.”

Shares of Chinese company ZTE, which has recently faced some trouble with the U.S. Department of Commerce over alleged trade violations, dropped 11 percent on the Hong Kong Stock Exchange on the news Friday. HTC’s stocks were down 3.2 percent, and Lenovo stocks were down around 2.6 percent.