Chinese software developers over the Green Dam Youth Escort monitoring program suffered several targeted attacks earlier this week, when documents containing malicious exploits were sent to attorneys, the firm stated late Wednesday.

On Monday evening, lawyers at the firm of Gipson Hoffman & Pancione received e-mails that appeared to have been sent by associates, the group said in its statement. The Trojan e-mail messages contained either links to Web sites or attachments and were specially constructed to retrieve data from the victim's computer or the company's server.

"The specific source of the attacks has not yet been determined, but it appears that they attacks were initiated within China," the firm said in its statement.

Last week, filtering software firm CYBERsitter announced that it had retained Gipson Hoffman & Pancione to sue the Chinese government, two Chinese software developers and seven PC makers for allegedly distributing its software code as part of the Chinese state-sponsored filtering and monitoring program known as Green Dam Youth Escort. The latest incident follows Google's announcement on Tuesday that it was considering pulling out of China following serious attacks on its networks that resulted in stolen intellectual property and the surveillance of human-rights activists in China.

The attacks on law firm GHP are not the first attempt to infiltrate companies involved in the claims against China and Green Dam. Last summer, CYBERsitter also received two PDF files containing malicious code.

The law firm has contacted the FBI and the U.S. government and the incident is under investigation, according to its statement.