Microsoft has no plans to pull out of China, its chief executive Steven Ballmer has confirmed, dashing hopes that the software giant would support its rival Google in its stand against Chinese censorship of the internet.

Asked if Microsoft had any plan to pull its business out of China, Mr Ballmer said “No.” before questioning the sudden urgency of Google’s complaints about attempts to hack Gmail accounts of human rights activists from inside China.

“I don’t understand how that [a Google pull-out] helps anything. I don’t understand how that helps us and I don’t understand how that helps China,” he said.

His remarks came as the PEN American Centre, the US freedom of speech group, condemned the arrest of another Chinese human rights activist earlier this week.

Zhao Shiying, secretary-general of the Independent Chinese PEN Center (ICPC), was taken from his home on Monday evening and has been held incommunicado ever since, the group said in a statement.

Mr Zhao, a well-known dissident writer from Shenzhen, was a signatory to the Charter 08 pro-democracy petition whose organiser, Liu Xiaobo, was sentenced to 11 years in jail last month for “subverting state power”.

“We are deeply troubled by the detention of Zhao Shiying, the latest in a string of arrests and detentions of members of the Independent Chinese PEN Center,” said K. Anthony Appiah, President of PEN American Center.

“We call on the government to release Zhao Shiying immediately, and to stop propagating this campaign against all citizens of China who are simply expressing themselves peacefully in accordance with their rights under Chinese and international law.”

Microsoft’s stance will disappoint activists who had hoped other major US technology giants would support Google and comes despite calls from senior Republican politicians for US tech heavyweights to speak out against Chinese censorship.

On Tuesday, Google shocked the corporate world by threatening to pull out of China if it wasn’t allowed to operate free from censorship.

The company cited cyber attacks from within China as the final straw in a long-running battle against the Chinese authorities since setting up its Chinese operations in 2006.

However Mr Ballmer, whose company’s search engine Bing could benefit if Google surrenders its 30 per cent share of the Chinese search market, questioned the significance of the cyber attacks which Google detected in December and affected more than 30 major corporations.

“There are attacks every day. I don’t think there was anything unusual, so I don’t understand,” he said, “We’re attacked every day from all parts of the world and I think everybody else is too. We didn’t see anything out of the ordinary.”

The Obama administration has given full support to Google, demanding an ‘explanation’ for the hacking attacks which it said raised ‘very serious concerns’ about both freedom of speech and the trust needed to underpins a globalised economy..

“It seems to me that the principles that Google is trying to uphold are not just important in a moral or rights framework, but are also of very considerable economic importance,” said senior White Senior White House economic adviser Lawrence Summers on Thursday.

China has so far shown no signs of giving ground over Google’s demand to be allowed to operate in China uncensored, insisting that web controls are essential to maintain the “stability and harmony” of the Chinese nation.