China's top search engine Baidu has filed a law suit against Register. com Inc which is its domain name service provider, on Wednesday after a cyber attack which severely affected its services last week.

A group which called itself the Iranian Cyber Army hacked into the site on Jan 12 and routed the users to a page created by them. The page featured the Iranian national flag and a message which read "This site has been hacked by Iranian Cyber Army." This group is also believed to be behind the attacks on twitter in December.

There was some retaliation as Chinese hackers attacked Iran based sites the next day.

The attack had left Baidu’s search engine unusable for several hours. Security experts point out that the hackers had changed Baidu's DNS records and thus redirected users to their page.

An email statement from Baidu said "As a result of the gross negligence of Register. com Inc, the domain name resolution of www. baidu. com was unlawfully and maliciously altered."

The suit accused Register. com of breach of contract and "gross negligence," and Baidu said it was seeking damages for violation of the Lanham Act. Baidu also laid charges on trademark infringement.

The court document said "Baidu's account was vandalized so that Internet traffic intended for Baidu and accessed through the 'baidu. com' domain name was misdirected to a web page depicting an Iranian flag and a broken Star of David."

Baidu did not disclose estimated losses or the amount it was seeking in damages through the law suit filed in Manhattan federal court in New York. While in other development, Baidu CTO Yinan Li has resigned from the job citing personal reasons.

Baidu is currently the market leader in the Chinese market with a market share of about 70%. The shares of the company listed on Nasdaq touched $470.25 last Friday, recording a rise of about
20%.