US-based respiratory devices manufacturer ResMed has filed a new complaint with the International Trade Commission against Chinese firm BMC Medical and its US sales subsidiary 3B Products.

Earlier, the firm sued BMC and 3B, alleging that the two firms infringed on its patents for CPAP, nasal pillows patient interface and nasal mask devices.

This week, the respiratory devices maker said it amended the case and included some more patents.

ResMed global general counsel and chief administrative officer David Pendarvis said, "ResMed built its market leadership by investing in superior technology for sleep-disordered breathing therapy.

"We will continue to defend our proprietary technology by enforcing our patents against those who unfairly copy our products," Pendarvis added.