The cyber criminals who hacked into Google's systems may have attacked more than 100 other companies, according to new information from security consultancy Isec Partners.

Google announced in January that its systems had suffered a hacking attack, indicating at the time that "at least 20 other large companies from a wide range of businesses, including the internet, finance, technology, media and chemical sectors, have been similarly targeted".

Other estimates put the figure at more like 30 companies, naming Symantec, Adobe and Intel as potential victims.

However, Isec Partners estimates the number of affected companies to be more than 100, having discovered a larger number of command and control servers involved in the attack.

"Further investigations have uncovered that more than 100 companies may have been targeted, although it is difficult to ascertain how closely related these attackers are to Google's assailants," said Alex Stamos, a partner at Isec Partners.

Details of the hack are emerging all the time, and much of the focus has centred on whether it was sanctioned by the Chinese government. The latest reports seem to indicate that a known security researcher wrote the hacking code and posted it on a forum, where it was picked up by Chinese officials.

However, recent remarks by Google co-founder Sergey Brin suggest that it makes no difference to Google whether the Chinese government was responsible for the attack or not.

"I think that the Chinese government has tens of millions of people in it. If you look at the army, the associated army and whatnot, that's larger than most countries’ by far," he said at a recent conference in California.

"So even if there were a Chinese government agent behind it, it might represent a fragment of policy as it were."