Some security analysts said the media attacks were probably linked to the Beijing authorities, while others argued it was difficult to ascertain whether the attacks stemmed from China or if hackers acted on government orders.
"The Chinese government clearly has the capability of doing this," wrote the founder of a group, Greatfire.org, that monitors Chinese internet controls, a system termed the Great Firewall.
"Online censorship in China is both massive in scale and sophisticated, meaning that they have to employ very skilled people," he said, using the pseudonym Martin Johnson for security reasons.
Still, finding hard evidence to tie the attacks to the Chinese government was "nearly impossible," said his co-founder "Percy Alpha".
Hackers from China have previously been linked to attacks on US defence giant Lockheed Martin, Google and Coca-Cola. Other reports say Chinese hackers have tried to infiltrate the Pentagon's computers and those of US lawmakers.
Beijing's defence and foreign ministries last week repeatedly rejected any accusations of hacking.
"Cyber-attacks have a transnational and anonymous nature," the defence ministry said in a statement to AFP. "Under such circumstances accusing the Chinese military of launching attacks through the web without irrefutable proof is unprofessional and baseless."
Sign up for CIO Asia eNewsletters.