Google's executive chairman, Eric Schmidt, warned on Wednesday that government plans to block access to illicit filesharing websites could set a "disastrous precedent" for freedom of speech.

Speaking to journalists after his keynote speech at Google's Big Tent conference in London, Schmidt said the online search giant would challenge attempts to restrict access to the Pirate Bay and other so-called "cyberlocker" sites that encourage illegal downloading – part of government plans to fight online piracy through controversial measures included in the Digital Economy Act.

"If there is a law that requires DNSs [domain name systems, the protocol that allows users to connect to websites] to do X and it's passed by both houses of congress and signed by the president of the United States and we disagree with it then we would still fight it," he added. "If it's a request the answer is we wouldn't do it, if it's a discussion we wouldn't do it."

Schmidt, who became Google's executive chairman last month after a decade as its chief executive, described website blocking as akin to China's restrictive internet regime.

"I would be very, very careful if I were a government about arbitrarily [implementing] simple solutions to complex problems," he said. "So, 'let's whack off the DNS'. Okay, that seems like an appealing solution but it sets a very bad precedent because now another country will say 'I don't like free speech so I'll whack off all those DNSs' – that country would be China.

"It doesn't seem right. I would be very, very careful about that stuff. If [the UK government] do it the wrong way it could have disastrous precedent setting in other areas."

Speaking at the same conference, the culture minister, Jeremy Hunt, said plans to block access to illicit filesharing websites were on schedule. He admitted that a "challenge" of the controversial measure is deciding which sites get blocked.

Ofcom is due to present its report on the practicability of the site-blocking measures included in the DEA to Hunt in the coming weeks.

Responding to questions about Facebook secretly hiring the public relations firm Burson-Marsteller to plant scare stories over Google's privacy policies in the US media, Schmidt said he would not comment.

However, he added: "A lot of people – not Google employees – have looked at these claims and generally found them to be false."