Samsung has filed another lawsuit against Apple, claiming the iPhone 4S and iPad2 infringed on three of its patents.
This escalates the tension between the firms as they fight for dominance of the mobile device market, after a series of legal clashes in Australia, Germany, and the Netherlands.
Samsung said the fresh suit, filed this week to a Seoul court, covers three utility patents and involves methods of displaying data, the user interface, and short text messages.
The companies have extended their fight to more than 30 cases in 10 countries since Apple fired its first salvo in April, claiming Samsung "slavishly" copied its iPhone and iPad models.
Samsung counter-sued, saying Apple infringed on its patents and failed to pay royalties.
Apple is also involved in patent battles in separate disputes with other smartphone makers using Google's free Android platform, the fastest growing mobile operating system, which is used by Samsung, Motorola Mobility and HTC.