Business networking site LinkedIn appeared to have been blocked in some parts of China, the company said.
No explanation was given for the move, which LinkedIn is still investigating.
However, it comes amid a renewed clampdown on internet discussion groups and micro blogging sites by authorities in Beijing.
Shortly before the site went offline, one user set up a forum, discussing the idea of a "Jasmine Revolution" in China.
The phrase has been used to describe the popular revolts taking place across Egypt, Tunisia, Libya and several other countries.
Over the weekend, a number of pro-democracy demonstrations were held across China, with police making a handful of arrests.
The protests are thought to have been organised in response to calls made on the website Boxun.com, access to which is banned inside mainland China.
Shortly afterwards, a LinkedIn user named Jasmine J created a group called Jasmine Voice.
In one posting, they wrote: "OMG, some pro-democracy fighters really did something here after the triumph of Egypt."
However, the message does not appear to be strongly for or against a Chinese revolution.
"The revolution here means turn the Chinese political system into multi-party democratic election and separation of the three powers. Who need this?" wrote Jasmine J.
At this stage, there is no evidence that the Chinese authorities were responsible for disrupting access to LinkedIn.
However, in a statement, company spokesman Hani Durzy said: "This appears to be part of a broader effort in China going on right now, involving other sites as well."
Some users in China reported that their access to LinkedIn had been restored during Friday.
China already exercises strict control over what citizens can view online, with many websites and politically sensitive subjects blocked.
Authorities appear to have increased the level of filtering in response to the wave of popular uprisings across the Middle East.
Searches for the word "jasmine" are now blocked on the country's most popular website, Sina.com.
Internet users inside the country reported that some sites were also blocking information on Jon Huntsman, the US ambassador to Beijing.
Mr Huntsman was seen attending one of last weekend's pro-democracy rallies.
Campaign group Reporters Without Borders criticised the escalation in Chinese net censorship, accusing the authorities of trying to stamp out "all forms of freedom of expression".
In a recent speech, Chinese President Hu Jintao stressed the need to "build a socialist social management system."
He added: "Unhealthy practices that could harm people's rights and interests must be corrected resolutely."