In yet another twist in a series of patent wars with Apple Inc., Samsung Electronics Co., the world's largest smartphone maker, has submitted an appeal of a June ruling by a U.S. agency which said the iPhone maker was not infringing upon some of the South Korean company's patents, industry sources said Monday.

Samsung's appeal in the U.S Court of Appeals for the Federal Circuit came as U.S. President Barack Obama last week issued a veto on a patent ruling by the International Trade Commission (ITC) that bans the import of some older models of the iPhone and iPad, dealing a blow to Samsung in its ongoing patent dispute with Apple, the world's second-largest smartphone vendor.

On June 4 of this year, ITC ruled that Apple infringed upon one of Samsung's standard-essential patents, putting the ban on older Apple devices such as the iPhone 3GS, iPhone 4, iPad 3G and iPad 2 3G.

Samsung is expected to claim that its commercial patents, not standard-essential patents, are being infringed upon by Apple.

Market watchers said the U.S. government's decision was based on the so-called Fair, Reasonable and Non-Discriminatory (FRAND) standard, which was introduced to prevent patent owners from abusing their power.

The FRAND license standard also prevents holders of patents from denying market access to latecomers.

This decision was the first time that the U.S. government has vetoed a ruling by the ITC in 25 years. The ITC is an independent federal agency -- working with the Department of Commerce -- that determines the impact of imports on U.S. industries and directs actions against unfair trade practices such as subsidies, dumping and infringements of patents, trademarks and copyrights.

The ITC, meanwhile, plans to announce its final ruling on Apple's patent claim against Samsung on Aug. 9.

The upcoming reviews will decide whether to uphold a preliminary ruling by the ITC that stated Samsung's older mobile devices, including Galaxy S2 models, infringed on four patents held by Apple. (Yonhap News)