Samsung Electronics said on Friday it has filed a lawsuit against Apple alleging patent infringements, days after the US technology firm took the South Korean company to court on similar grounds.
Samsung said it filed suit on Thursday in a Seoul court alleging five patent infringements by Apple. Separate suits were filed in Tokyo citing two patent infringements and in the German city of Mannheim citing three.
"Samsung is responding actively to the legal action taken against us in order to protect our intellectual property and to ensure our continued innovation and growth in the mobile communications business," the company said in a statement which gave no details of the alleged infringements.
The announcement came a week after Apple filed suit against Samsung in San Francisco claiming that the South Korean giant copied its smartphones and tablet computers.
Apple's lawsuit says Samsung's mobile phones and Galaxy Tab imitated the iPhone and the iPad. Samsung vowed at the time to "respond actively".
The Galaxy Tab has been the best-selling rival to the iPad, which has dominated the growing market for the touchscreen devices.
Despite their prickly competition in finished products, the two firms have a close business relationship.
Apple was Samsung's second-largest client in 2010 after Japan's Sony Corp, accounting for four percent of the South Korean firm's 155 trillion won ($142 billion) annual revenue.
"We are Samsung's largest customer (for liquid crystal display panels and semiconductors) and Samsung is a very valued component supplier to us," Apple chief operating officer Tim Cook said on Wednesday in the United States.
But Apple filed its lawsuit because the Korean company had "crossed the line", he said.
In comments on Thursday, Samsung's chairman Lee Kun-Hee said Apple was trying to keep his company in check.
"It's like the proverbial nail that sticks out gets hammered down," Lee told reporters, according to Yonhap news agency.
"Not only Apple, but also unrelated companies that do not produce electronics products are increasingly trying to keep Samsung in check."