The large distributed denial of service (DDoS) attacks that hit WordPress.com last week originated from China, according to the founder of the site.

A DDoS attack involves harnessing hundreds or thousands of computers to simultaneously bombard a website with data so it becomes overwhelmed. The computers in such attacks have typically been infected with malware so they can be used without the consent and awareness of their owners.

The attacks, which brought slowdowns to the WordPress.com site, were severe enough to interfere with the company's three datacentres in Chicago, San Antonio and Dallas. The site has since returned to normal,  as of Monday.

WordPress said last week that the attacks might have been politically motivated and aimed at an unnamed Chinese-language blog, but it no longer has that view.

"Don't think it's politically motivated any more," said WordPress Founder Matt Mullenweg. "However, the attacks did originate in China."

Mullenweg did not elaborate on the change in view or offer details on the source of the attacks.

The attacks directed "multiple Gigabits per second and tens of millions of packets per second" and were the "largest and most sustained" in its six-year history, Mullenweg previously said.

China has been named as the country of origin for several major cyberattacks. Chinese hackers have been accused of launching cyberattacks to steal gigabytes of data from foreign energy companies, according to security vendor McAfee. In 2009, Google was also the victim of an attack that it alleged originated from China.

Very often the true source of a DDoS attack is unclear. While computers launching the attacks might be based in one country, they could be under control of hackers in a third country. Users at high risk of malware infections that can be used for DDoS attacks are those that don't run antivirus software, don't keep their operating system updated or are running pirated operating systems that can't be updated.

The Chinese government has responded to these reports, saying it denies being involved in any cyber attacks. "The allegation that China supports hacking is groundless," a China foreign ministry spokesman said last month.