Google’s (NASDAQ:GOOG) search engine and email, among other services, are being interrupted in China ahead of this week’s 25th anniversary of the 1989 violent suppression of pro-democracy activists in Beijing’s Tiananmen Square, an online censorship watchdog reported Monday., which has monitored China’s blocked websites and keywords since 2011, said the Chinese government appears to have begun blocking Chinese users’ access to many of Google’s services since last week.

This is the first such block the organization has recorded since one in 2012 that lasted 12 hours.

"It is not clear that the block is a temporary measure around the anniversary or a permanent block. But because the block has lasted for four days, it's more likely that Google will be severely disrupted and barely usable from now on," the advocacy group said.

A Google spokesman told Reuters: "We've checked extensively and there's nothing wrong on our end."

Google’s transparency report shows Internet traffic from China has slowed since Friday.

The Chinese government blocks many popular foreign websites, including Facebook, Twitter and Google-owned YouTube. China also imposes strict regulations on what can be said online.