Chinese authorities have blocked the search engines of two of the country's most popular Web portals as part of their efforts to censor the Internet, industry sources, quoted by an AFP report, said.
The report said the search engines at and had been shut down since noon Monday.
Searches conducted brought up messages saying the sites were undergoing upgrades, the report said.
China had for years been waging an online battle to censor the Internet of pornographic and violent content, and to seek to stifle political and religious material that it believed could spark social unrest, the report said.
"As of yesterday noon, all the databases have been in a state of closure because relevant government Internet supervision departments were censoring our databases," the source, a member of the customer service staff at told AFP. "It affects not just Sina, but Sohu as well, so our search engines are not in use."
The report further said that another member of the Sina staff confirmed the government order, although the company spokeswoman's office declined to give a reason, saying the system was only going through an upgrade.