The US government is planning to formally request a response from the Chinese government to Google’s report of a cyber attack on the search engine’s corporate infrastructure in a major attack that took place in December of 2009 and targeted several other large US technology firms, AFP reported Friday.

The news service quoted US State Department spokesman P.J. Crowley as saying, “It will express our concern for this incident and request information from China as to an explanation of how it happened and what they plan to do about it.”

Google said the attack and recent attempts by the Chinese government to further sensor Web content that reaches Internet users in the country had lead the company to reconsider its agreement to filter certain results returned by the Chinese version of its search engine - largely results that are politically inconvenient for the government.

The company said earlier this week that it will seek to discontinue filtering the results and if it is not able to come to an agreement with the Chinese government, it will pull all of its operations out of the country.

The attack, whose targets included data center and managed services provider Rackspace, were reportedly aimed at Gmail accounts of activists for human rights in China and Google said it had evidence that the attack originated in China.

Other companies that reported having been targets in the attack reportedly included Yahoo!, Adobe, Symantec and Juniper.

In a Thursday blog post, Microsoft’s Director of Security Response Mike Reavey wrote that “a vulnerability in Internet Explorer appears to be one of several attack mechanisms that were used in highly sophisticated and targeted attacks against several companies.”

Reavey said there was no indication of attacks on Microsoft’s own corporate network or mail properties.