BEIJING: A move by China's authorities to strip Sina Corp of some online publication licences as part of a pornography crackdown should be seen as a warning shot at the country's Internet firms to toe the Party line on freedom of expression, experts said. 

The punishment was also initiated by a regulatory body that has previously not exercised its power in this way, and is being widely viewed as a sign that various branches of the government are clamouring to assert their authority over the Internet.