China's government has accused the country's leading internet search engines and web portals, including Google, of threatening public morals by carrying pornographic and vulgar content.

While Beijing regularly launches web censorship campaigns, the new crackdown is the first to target large companies such as Google and Baidu, the former's homegrown rival that leads the Chinese search market. In the previous campaign, a year ago, officials accused only small and little-known sites of carrying unhealthy content.