China's broad crackdown on dissent that has seen activists get lengthy jail terms and human rights lawyers disappear stems from a mix of arrogance and insecurity in Beijing, the most recently exiled Chinese dissident said on Wednesday.

Behind the pride and conceit of the Chinese government there's a great sense of crisis and vulnerability, said Yu Jie, one of China's most prominent Christian dissidents, who ran afoul of Beijing for critical writing and for his close ties to writer Liu Xiaobo, the 2010 Nobel Peace laureate.

In his first public appearance after he arrived in the United States with his family last week, Yu described a near-death experience at the hands of police torturers, quoting one as saying We'll pound you to death to avenge this (Liu's Nobel).

Liu was convicted in 2009 on charges of inciting subversion and sentenced to 11 years in jail. His jailing and the secretive house arrest of his wife Liu Xia have become the focus of an international outcry over China's punishment of dissent.

Picked up by state security officers in Beijing the day before Liu's award ceremony in Oslo, Yu said he was taken to a secret location, beaten, stripped and kicked by plainclothes officials who threatened to post his naked pictures online.

Yu told a news conference that his captors burned his face with cigarettes, kicked and slapped him repeatedly. He was taken to the hospital for life-saving emergency treatment. When Yu tried to tell a doctor he'd been beaten, a security official threatened to pull out all of the tubes from your body and let you die.

If the order comes from above, we can dig a pit to bury you alive in half an hour, and no one on earth would know, Yu quoted one of his police interrogators as saying.

REPRESSION WORSENING, US ENVOY SAYS

Human rights groups have recorded worsening conditions for dissidents, lawyers and outspoken writers in China since the 2010 Nobel Prize decision infuriated China, if not earlier.

U.S. ambassador Gary Locke said in a televised interview this week that the human rights situation had deteriorated since before the 2008 Beijing Olympics.

The human rights climate has always ebbed and flowed in China up and down, but we seem to be in a down period and it's getting worse, Locke told U.S. talk show host Charlie Rose on Monday.

There's a significant crackdown and repression going on within China, he said in remarks that drew a swift denial from China's foreign ministry.

Chinese officials were not immediately available to comment on Yu's torture allegations. Last week Chinese Foreign Ministry spokesman Liu Weimin said he knew nothing about Yu.

Locke attributed the crackdown to the Chinese leadership's fears that a movement like the Arab Spring could happen in China. Other analysts say China's Communist Party is tightening controls over society ahead of a leadership handover late this year from President Hu Jintao to Vice President Xi Jinping.

Asked how he explained the ongoing crackdown, Yu again quoted the security official who oversaw his mistreatment in 2010, saying it represented official arrogance and sense of impunity fuelled by China's economic success.

He said: 'The Chinese government has lots of money and we are going to do whatever we want to do,' Yu told a news conference in Washington.

Yu, 38, said he enjoyed relative freedom to write until he was totally blocked when China's current leadership team of President Hu Jintao and Premier Wen Jiabao came to power a decade ago.

Yu published a scathing book about Wen that was cited by police as one of his crimes and says he plans to put out Hu Jintao: Cold-Blooded Tyrant in 2012.

The soft-spoken and bookish-looking writer said the political transition in China will not make any difference.

Whether it's Hu Jintao, Wen Jiabao or their future successors Xi Jinping and Li Keqiang, they are all representatives or surrogates of this elite interest group. They are not going to initiate political reform, said Yu.

(Editing by Philip Barbara)