SAN FRAN­CIS­CO - Ya­hoo is bring­ing out more ar­tillery in its patent bat­tle with Face­book. It is adding new al­le­ga­tions of in­tel­lec­tu­al prop­er­ty theft to its six-week-old law­suit against Face­book. In court pa­pers filed Fri­day, Ya­hoo Inc. now says Face­book's on­line so­cial net­work in­fringes on 12 of its In­ter­net patents, up from 10.

Ya­hoo al­so de­nied al­le­ga­tion that it has been in­fring­ing on 10 of Face­book's patents and ac­cused its ri­val of en­gag­ing in shady be­hav­ior. Among oth­er things, Ya­hoo says Face­book vi­o­lat­ed an agree­ment be­tween the two com­pa­nies to no­ti­fy each oth­er of pos­si­ble patent in­fringe­ments be­fore fil­ing a court claim.

"We re­main per­plexed by Ya­hoo's er­rat­ic ac­tions," Face­book said in a state­ment. "We dis­agree with these lat­est claims and we will con­tin­ue to de­fend our­selves vig­or­ous­ly." Ya­hoo ques­tioned Face­book's in­tegri­ty in the new fil­ing in San Fran­cis­co fed­er­al court. It said Face­book re­cent­ly bought sev­er­al patents for the sole pur­pose of counter-su­ing Ya­hoo and then guessed which Ya­hoo ser­vices might re­ly on the tech­nolo­gies cov­ered by the in­tel­lec­tu­al prop­er­ty rights.

AP