A Google Web site that monitors access in China is reporting that Google Web search, which was fully or mostly accessible yesterday in mainland China is being completely blocked. But the company is now saying that service is fine.

The company's stock had slipped nearly 2% in after-hours trading as of 6 p.m. EST.

Google.cn has been blocked multiple times in China, most recently a month ago, before China chose to renew the company's Internet Content Provider license.

Google had been automatically redirecting google.cn to google.hk, its uncensored site in Hong Kong, but stopped that practice earlier this month and simply included a link to google.hk on the google.cn site in order to pacify Chinese lawmakers.

Shares of the state-supported Chinese search competitor Baidu jumped 3% after the news.

Google Mobile and Ads were fully blocked, and News and Images were partially blocked today, according to Google.

The Chinese information ministry purposefully makes it difficult to tell if access is being blocked from the top. But the Chinese government's history of blocking the search engine suggests this is a deliberate move.

UPDATE: Some Twitter users in China are reporting they have full access to google.cn, Rebecca MacKinnon and others reported. However, the service may still be blocked for others, or even for most individuals in China. At the least, it appears that it is blocked for the computers distributed around the country that Google uses to monitor availability.

From the page where Google monitors access in China: "The status is assessed by geographically diverse servers that are used to monitor connection capability. Note that service status in China has a fluctuating nature. This assessment may not reflect small-scale blocking that frequently occurs or individual experiences with issues such as keyword blocking that may affect access to services temporarily."

LATE UPDATE: At least 10 Twitter users in China have said that google.cn is working. Google's stock still down 1.59% at 7:40 p.m. EST. Google's China access monitoring site still says services are blocked; no statement yet from the company.

LATEST: Google says service is working in China. A Google spokesman sent this statement:

"Because of the way we measure accessibility in China, it's possible that our machines could overestimate the level of blockage. That seems to be what happened last night when there was a relatively small blockage. It appears now that users in China are accessing our properties normally.

"Please also note that the dashboard is not a real time tool."

Google's stock was still down more than 1% at the time of this update but appears to be recovering.

Below: Google's chart tracking availability of services in China.