Complains China Shut it Down, an online human rights activist organization, is complaining that it is the victim of cyber-attacks from China aiming to bring the site down to stop readers from signing a petition demanding the release of artist Ai Weiwei.

Ai, one of China's most famous artists, was detained on April 3 in Beijing as he was about to board an airplane for Hong Kong. His whereabouts have been undetermined since. Although Chinese news sites have indicated he would be charged with economic crimes, his arrest is universally assumed to be because of protests he has led over substandard construction that left 5,000 children dead in an earthquake two years ago, among other issues.

Although Chinese hackers may have brought down the site, it remains off the Internet because of a problem that originated with the Internet retailing giant The site Friday night Hong Kong time said it is down because its servers are connected to Amazon, whose hosting fees are some of the cheapest. Amazon's EC2 web-hosting service suffered a technical problem that took some of the web's biggest social media sites offline. Amazon is the world's biggest cloud-computing provider.

Amazon's website said most of its services are operating normally although some cloud computer operations operating from northern Virginia remain offline because of problems. runs petitions on a variety of social change issues including gay rights, women's rights, animal welfare and others. The petition demanding Ai's freedom had garnered nearly 100,000 signatures, according to a release by The organization said it has been attacked repeatedly by Chinese hackers over the last year.

"For the past three days, the website has been repeatedly targeted by cyber attacks coming from China that aim to bring our site down, which would keep people from signing the petition, the organization said in a press release." Our engineers are working around the clock to fend off the attacks and, for now, the petition is still up. We need to let the Chinese government know that illegal tactics from within its borders won't stop the mounting pressure on them to release Weiwei."

Attempts to reach were unsuccessful. However, Ben Rattray,'s chief executive officer, told the Bloomberg news service that attacks on the site over the past three days originated from Chinese Internet addresses. Ratray told Bloomberg that had reported the attacks to US government agencies including the Federal Bureau of Investigation.

Li Wufeng, chief of the Information Office Internet Affairs Bureau of China's State Council, or cabinet, didn't return a call to his office seeking comment, Bloomberg said.'s campaign "has helped to give rise to an international outcry," the organization said in its press release. "Political leaders around the world are calling for Weiwei's release and activists have organized peaceful protests at Chinese embassies and consulates. Though China is desperate to silence its critics, the pressure to free Weiwei continues to grow. You can help by signing the petition now: warned that because of the repeated attacks the site might be slower than usual or unavailable over the next few days. The press release did not mention the problem.