Google is investigating the possibility that its own employees played a role in a major cyber attack in December, it has been claimed.

Sources familiar with the matter told Reuters news agency that the strike may have been instigated by workers at Google’s offices in China. If local reports are to be believed, a number of the search engine’s Chinese employees have been placed on leave or denied access to internal networks following last week’s revelation that hackers attempted to breach a number of Gmail accounts.

Google has so far refused to comment on either allegation, while also denying that it is resigned to withdrawing from the Chinese market following its announcement that it will no longer censor its search results, as required by the government.

The December attack, which is said to have affected more than 20 other organisations as well as Google, exploited a security flaw in the Internet Explorer browser, Microsoft conceded last week.