With a little more than a day before the iPhone 5's expected debut, Samsung has decided to sue Apple for patent infringement over its reported use of long-term evolution (LTE) connectivity in the next-generation smartphones.

Expected to be unveiled at a press event in San Francisco on Wednesday, the iPhone 5 will reportedly feature the speedier fourth-generation wireless networking, for which Samsung holds numerous patents. Samsung, which has been locked in a series of high-stakes patent trials with Apple, had previously threatened to sue the iPhone maker if it were to release LTE-enabled products.

After reports Monday of LTE capability on the iPhone 5, the South Korean electronics giant "has decided to take immediate legal action," an industry source tells the Korea Times. Europe and the United States "are our primary targets," the source said.

CNET has contacted Samsung and Apple for comment and will update this report when we learn more.

The revelation comes on the heels of a U.S. trade judge hinting that Apple might not be able to persuade him that a pair of HTC patents related to 4G LTE technology should be invalidated in a case that could lead to an import ban on the latest iPad and the forthcoming iPhone 5.

U.S. International Trade Commission Judge Thomas Pender said Thursday that "clear and convincing means something to me," addressing the guidelines for determining whether a patent should have been issued. "I have to be pretty darn certain a U.S. patent is invalid."

4G LTE technology was largely expected to be included in last year's iPhone model, the iPhone 4S. Apple chose instead to go with HSPA+, a slightly speedier 3G technology, but a far cry from what can be had on the 4G LTE spec, which can be 10 times as fast.