Another lawsuit has been filed against Apple Inc. in South Korea by Samsung Electronics Co., with the latter claiming that the iPhone 4S and iPad2 infringed on three of its patents.

The move intensifies the tension between the firms as they compete for dominance of the mobile device market, after a series of legal clashes in Australia, Germany and Netherlands.

Samsung says the fresh suit, filed on Tuesday 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 Holdings and HTC Corp.