China said on Tuesday that Google Inc had violated a written promise and was totally wrong to end censorship of its Chinese-language search portal, signaling a tough line over the Internet dispute.

An unnamed official from China's State Council Information Office, which helps oversee Internet rules, made the comments after Google started redirecting users of its China mainland-based site to a portal in Hong Kong, ending self-censorship of its Chinese-language searches.

The official's comments suggested Google could not expect an easy time from mainland authorities, over two months after the company said it would no longer accept self-censorship of its site and was also alarmed by sophisticated hacking attacks coming from China.

Google has violated the written promise it made on entering the Chinese market, the official said, according to a report from the China News Service, a state-run news agency.

It is totally wrong in halting (censorship) filtering of its search provider and also making aspirations and accusations toward China about hacking attacks, said the official.

We firmly oppose politicizing commercial issues, and express our dissatisfaction and anger at Google Inc's unreasonable accusations and practices, said the official.

The State Council Information Office is the government arm of China's propaganda apparatus, and is among several agencies overseeing Internet policy for the ruling Communist Party.

China censors the Internet by requiring domestic operators to use filters to screen out banned images and words, and also operates a firewall to frustrate users trying to access overseas websites that are deemed unacceptable.

The official said that Chinese government officials held talks with Google twice -- on January 29 and February 25 -- to discuss the dispute.

In those talks, China warned Google that if it chose to shut its China-based search portal, it would have to do so according to Chinese law and also ensure that left-over problems were handled responsibly, said the report.

(Reporting by Chris Buckley, editing by Tim Pearce)