China's Sina.com reports that search engine Google is once again experiencing difficulties in China as, from 5:00pm on Sunday October 19, Internet users were unable to access the Google.com site or perform any searches.

As of 11:30AM, October 20, Google is still inaccessible through normal Internet routes in Beijing and Shanghai.

Chinese reporters made inquiries with two of China's largest web-searching companies to ascertain what the trouble might be, but failed to receive satisfactory answers as the companies' technicians were unable to confirm even whether the problems were technical or not. After testing other Google IP (Internet Protocol) addresses, technicians found that those websites ran normally–only www.google.com and some IPs such as the news search engine were affected.

The most likely cause is a DNS error, but as Google is located outside China, the details are still not clear, though if this is the cause, then repairs might be expected to take from 24 to 48 hours.

This is not the first time that Google has experienced troubles in China: in September last year, the search engine and several rivals were inexplicably unavailable on the mainland. It is reported today that other sites, including www.altavista.com, www.alltheweb.com, and Yahoo's search engine, are similarly inaccessible. Because of the other blocks of sites, some analysts wonder if the blocks are deliberate.

This trouble once again heavily weakens Google's market development–it was previously announced that some mainland web service providers in the south of China had met with Google regarding advertising–this new blow may severly reduce mainland companies' confidence.