Sleep apnoea device giant ResMed has responded to a patent dispute raised in the United States by rival Fisher & Paykel Healthcare with an infringement complaint of its own.
ResMed has filed complaints in a California court alleging patent infringement in a range of sleep apnoea treatment masks produced by Fisher & Paykel.
The filing follows a lawsuit brought by Fisher & Paykel alleging patent infringement by ResMed in a number of air pressure devices produced by the ASX- and New York Stock Exchange-listed company.
ResMed has also filed proceedings in the US, New Zealand and Germany seeking judgments that it does not infringe several Fisher & Paykel patents.
Fisher & Paykel said, in a statement on Thursday, that it "intends to vigorously defend" the allegations made by ResMed.