The Guardian reports that China and Google (GOOG) are at it again.  Google is now accusing China of  tampering with access to Gmail from within China. Customers and advertisers have increasingly been complaining to Google about their Gmail service in the past month. Attempts by users to send messages, mark messages as unread and use other services have caused issues that Google can’t account for.  Google concludes it must be China

“Relating to Google there is no issue on our side. We have checked extensively. This is a government blockage carefully designed to look like the problem is with Gmail,” said a Google spokesman. China’s embassy in Washington was not immediately available for comment.

Google even accuses China of blocking access to the Japanese People Finder database of missing persons from the Earthquake/Tsunami.

China and Google have had a very touchy relationship since Google found hackers inside its computer network looking for corporate secrets as well as accounts of Falun Gong and exiled Tibetans.  Google then pulled out of China and moved its operations to Hong Kong, a special administrative region of China not blocked by its firewalls.  Users in China are permitted to use the Hong Kong search engine to search for products.

Things have cooled down since, though Google services like YouTube are blocked in China.

The move to block Gmail isn’t just a consumer headache.  International firms who use Google Apps for Domains may experience issues when trying to access their corporate email, though no problems specifically related to business accounts have yet been reported.