The United States is playing a game of "cat and mouse" on the web, funding new technology aimed at breaking internet censorship in repressive regimes including China and Iran, officials have said.

Michael Posner, the US assistant secretary of state for human rights, said projects being funded by the US government included technology that acts as a "slingshot" – identifying censored material and throwing it back on to the web for users to find. The project is part of a $30m (£18m) state department project to encourage civil liberty online.

"We're responding with new tools. This is a cat-and-mouse game. We're trying to stay one step ahead of the cat," Posner said. Censored information would be redirected to email, blogs and other online sources, he said. He would not identify the recipients of funding for "reasons of security".

The comments are part of an overall US strategy to raise the importance of cyberspace in foreign affairs. The Pentagon is preparing to unveil an "international strategy for cyberspace" that will make online security an official domain of warfare like land, sea and air.

The comments came as the US ended two days of talks with Chinese officials amid worsening relations over censorship and crackdowns on dissidents. Posner said the US was using $19m to fund technology that would "be redirecting information back in that governments have initially blocked".

Chinese authorities block sites including Twitter and Facebook and censor information online. In March, Google accused China of interfering with its email service. Authorities have been censoring references to pro-democracy uprisings in the Arab world and blocked search results for "Hillary Clinton" after she gave a speech championing internet freedom.

Posner said the US was using $19m to fund technology that would "be redirecting information back in that governments have initially blocked.".

In Washington, critics have accused the state department of being slow to spend the money and kowtowing to China. Earlier this year senator Dick Lugar, a Republican on the Senate foreign relations committee, called for another government body to be put in charge of the funds.

Rebecca MacKinnon, co-founder of GlobalVoicesOnline.org, a global organisation for bloggers, said access to information was not the only issue people faced online. In Egypt, for example, censorship had not been a problem but, surveillance had been a far bigger issue, she said – when the revolution began, the authorities closed down the internet. MacKinnon said technology to help people avoid government scrutiny online and allow them to set up local networks should a regime pull the plug on internet access was just as valuable.

In a recent interview with the Atlantic magazine, Clinton said China had a deplorable human rights record and was involved in a "fool's errand" trying to hold off democratic changes like those sweeping the Middle East.

In her speech in February, the US secretary of state called the internet "the public space of the 21st century" and hailed the way it had been used to support uprisings in Egypt and protests in Iran. She pledged US support for freedom of expression and association online. "For the United States, the choice is clear. On the spectrum of internet freedom, we place ourselves on the side of openness," she said. But she criticised WikiLeaks for publishing secret US cables, calling it "an act of theft".