The China-based microblogging site is countering what it says are false news reports — including one about a murder — after the ruling Communist Party reportedly told Web firms last week to tighten controls online. Sina's (SINA) Weibo service sent letters to its 200 mil users denying 2 reports that were posted on its site. Chinese Internet companies are being pressed by Beijing to enforce censorship or risk being able to operate in the red-hot market. Shares edged up 0.1% to 98.