As of Friday, Chinese Gmail users now have no way to access their accounts. It's apparently the work of the Chinese government, which is blocking certain Hong Kong IP addresses used to access Gmail.

"We've checked and there's nothing wrong on our end," a Google spokesperson told Reuters.

The government started blocking the web version of Gmail in June of this year, around the 25th anniversary of the 1989 Tiananmen Square protests. The e-mail service was still available via third-party e-mail protocols like IMAP, SMTP, and POP3. Now it will be impossible to access Gmail from China at all without a tool that masks IP addresses, such as a VPN.

A Chinese Foreign Ministry spokeswoman said she had no knowledge of blocks.

However, an executive at Dyn Research told The Associated Press that his company's tests show the Chinese government blocked certain Hong Kong-based Google IP addresses used by Gmail users on the mainland.

Google stopped serving mainland China directly in 2009, saying it wouldn't abide by government censorship of search results. Google Sites, YouTube, and Picasa were shut down for Chinese users at various points during 2009, according to Google's transparency report. Google Search was still available until 2014.

The most widely used search engine in China is a locally grown one, Baidu. Before it was blocked in 2009, Google had a 31-percent share of Chinese search, but Baidu was still dominant.

Other popular US-based websites blocked by China include Facebook and Twitter. Some media sites have also been blacked out, such as The New York Times and Bloomberg News, which were blocked in 2012 after they published stories about the family wealth of Chinese leaders.