Computer hackers have attacked popular Chinese search engine, Baidu, forcing the site offline.

The attack is believed to have been carried out by a group calling themselves the Iranian Cyber Army – the same group that claimed responsibility for bringing down the social messaging site Twitter, last month.

According to a report by the BBC, Baidu users trying to use the search engine were directed to another website displaying a political message. The site was unavailable for around four hours.

A statement from the search engine firm said: “This morning, Baidu’s domain name registration in the United States was tampered with, leading to inaccessibility.”

Graham Cluley, a senior technology consultant at security firm Sophos, said: “In China, Baidu outranks Google as the search engine of choice, receiving millions of visits every day. That makes it an extremely attractive target for cybercriminals.

“Attacks like this are a reminder to everyone that you always need to have security scanning every webpage you visit, even if it’s a well-known legitimate website.”