China has hit back at the novelist Salman Rushdie after he argued that China had become “the world’s biggest threat to freedom of speech” in an article published earlier this month in The Daily Telegraph.

In an open letter titled “Human Rights lecture not needed”, China’s embassy in London attacked Mr Rushdie’s call for the release of Ai Weiwei, the Chinese artist behind the Tate Modern’s Sunflower Seeds, who has been detained since April 3.

“This is a blatant interference in China’s judicial independence and violates the country’s judicial sovereignty. This cannot and should not be accepted by any sovereign country,” said the letter published in China Daily, the Chinese government’s English-language mouthpiece.

“China is a country under the rule of law. The basic rights and freedoms of Chinese citizens, including freedom of expression, are protected by the law.

Chinese citizens can express their opinions and aspirations through many channels,” it added.

China’s protestations come the day after the head of a US human rights delegation to Beijing warned that the US government was “deeply concerned about the deterioration of human rights” in China over the last few months.

“It was a discussion that was very much based on the facts, and the facts are not good,” said Michael Posner, U.S. assistant secretary of state for democracy, human rights and labour, adding that the Chinese had provided no information about Ai Weiwei.

Mr Ai, a trenchant critic of the Chinese authorities who helped design the Olympic ‘Birds nest’ stadium in Beijing, has now been detained in unknown circumstances for more than 25 days without charge while he is investigated for “economic crimes”.

Over the last few months dozens of prominent members of China’s liberal fringe, including lawyers, artists, bloggers, Christians and journalists have been detained, harassed in a clampdown that Human Rights observers say is the worst for 30 years.

Mr Rushdie used his article to highlight several prominent cases including Ai Weiwei, the Nobel peace laureate Liu Xiaobo, who is serving an 11-year jail sentence for writing a pro-democracy petition, and the writer Liao Yiwu who was recently barred by the Chinese authorities from attending a literary festival in New York.

“Such figures as Ai Weiwei and his colleagues are often the only ones with the courage to speak the truth against the lies of tyrants,” wrote Mr Rushdie, who spent many years in hiding following the publication of his novel, *The Satanic Verses.* “We needed the samizdat truth-tellers to reveal the ugliness of the USSR.

Today China’s government has become the world’s biggest threat to freedom of speech, so we need Ai Weiwei, Liao Yiwu and Liu Xiaobo.” China has repeatedly batted away such allegations, preferring to concentrate on the rising standards of living it has delivered to its 1.3bn population through three decades of spectacular economic growth.

Since 2008 China has also grown increasingly strident in dismissing international pressure – whether from individuals or governments – recently warning the US not to use human rights as an excuse to meddle in its internal affairs.

“It is natural for China and Western countries to see human rights and democracy differently given their different historical and cultural traditions and national circumstances,” concluded the letter which dismissed Mr Rushdie’s comparison with the USSR.

“China is not the former Soviet Union,” it said, “China has no use for “lecturers”, who cling to the Cold War mentality and follow double standard in their preachings.”