Yahoo, Google, Microsoft and Cisco later responded to stinging criticism of their business practices – including accusations that they have “enthusiastically volunteered for China’s censorship brigade” – saying the issue was too big for the companies to tackle on their own and that the US government needed to take a leadership role.

The international relations sub-committee hearing on Capitol Hill was not the first time corporate executives had been taken to task by lawmakers for their business practices. But the presence at the hearing of Google and Yahoo, which pride themselves on facilitating the exchange of information around the world, and who have never before come under such harsh scrutiny, underscores that congressional pressure is building on the groups to take action to address concerns such as China’s human rights record.

Google on Wednesday admitted that its decision to enter the Chinese market and censor the results of its Google.cn website was “reasonable, though we cannot be sure it will ultimately be proven to be the best one”.

“If we determine that we are unable to achieve the objectives [we have set out], we will not hesitate to reconsider our approach to China,” said Elliot Schrage, vice-president of global affairs at Google.

Mr Schrage and other executives were at times left speechless under the relentless questioning of California congressman Tom Lantos, a Hungarian-born Holocaust survivor who asked each of the companies whether they felt “ashamed” and whether they would agree to discriminate against women if asked to by a repressive regime.

“Your abhorrent activities in China are a disgrace. I simply do not understand how your corporate leadership sleeps at night,” Mr Lantos said.

Dana Rohrabacher, a Republican legislator, emphasised the Chinese government’s persecution of minorities in China, and introduced Peter Yuan Li, a Chinese-born American who was beaten in his home in Georgia this month. Mr Li has accused Chinese agents of being behind the attack because of the work he has done as a software engineer trying to get controversial websites through Chinese firewalls. In a Financial Times interview, the Falun Gong practitioner described being subjected to a ferocious beating at his home by Chinese and Korean speaking men who stole two laptops and his home telephone.t.