Singapore Press Holdings (SPH), which is suing Yahoo! for copyright infringement, has accused the US Internet company of plagiarising its works. SPH, which publishes Singapore\'s Straits Times newspaper and other dailies, also vowed to fight a counterclaim filed this month by Yahoo! Southeast Asia alleging the media group infringed its copyright, the statement said. \"SPH is determined to pursue this suit vigorously and to protect its copyrighted works,\" the statement said, adding its defence to the counterclaim by Yahoo! had been filed Wednesday at the High Court. \"It cannot allow a third party to plagiarise its works without regard to the effort and resources that go into producing its content.\" SPH said in November it was suing Yahoo! for copyright infringement and wants the California-based web group to pay unspecified damages. Yahoo! rejected the allegations and on December 13 issued a counterclaim against the Asian publisher, saying copyright laws do not protect facts and information. The counterclaim also alleges the Asian publisher reproduced without authorisation several of its articles and pictures on STOMP, a citizen-journalism website owned by SPH. SPH said in its defence to the counterclaim that Yahoo! had gained commercially by reproducing its contents without permission. SPH said \"these acts of infringement were committed by Yahoo! to direct and maximise traffic to its website in order to drive up its page views and advertising revenue.\" Yahoo! is one of the top online sources of news in Singapore along with the Breaking News section of the Straits Times website, both of which can be accessed free of charge. The two services are competing for online advertising revenues along with Microsoft\'s MSN, which has a news tie-up with Singaporean broadcasting-based group MediaCorp. SPH is one of Asia\'s biggest media-based groups, with a near monopoly of Singapore\'s daily newspaper market and prime property assets. Group revenue in its financial year ending August 31 was down 9.4 percent from a year ago at Sg$1.25 billion ($960 million), but revenue from its newspaper and magazine business was up four percent at Sg$1.01 billion, according to its annual report.