Sony filed patent-infringement claims seeking to block LG Electronics from shipping mobile phones to the U.S. The complaints were filled Dec. 28 with the U.S. International Trade Commission in Washington, and in a federal court in Los Angeles. The ITC has the power to block imports of products found to violate U.S. patents, while the court can impose financial penalties.

According to the complaint, LG's Lotus Elite, Neon, Remarq, Rumor 2 and Xenon mobile phone models are using Sony technology without permission.

"After an internal review, we will actively respond with an appropriate action," Na Joo-young, an LG spokeswoman said in a telephone inquiry.

Sony plans to invest 100 billion yen ($1.2 billion) over the next fiscal year to double production capacity for image sensors used in smartphones.

LG is also trying to boost revenue at its consumer electronics, displays and handsets units by 13 percent in 2011. The company will increase its 2011 investment by 12 percent to a record 21 trillion South Korean won ($18.25 billion), in an effort to revive the struggling handset business of its core unit LG Electronics.

LG still lags behind Nokia and Samsung in sales of mobile phones, according to researcher Gartner Inc.

LG is also being targeted in Sony?s patent suit for its Blu-ray disc players.