A Chinese court jailed a veteran dissident to seven years in jail on Friday, his son said, in the latest blow to challengers of the Communist Party's rule before its presumed next leader, Xi Jinping, visits the White House.

Zhu Yufu was jailed for inciting subversion of state power by a court in Hangzhou, a city in eastern China, after a trial hearing on January 31 when prosecutors cited a poem and messages he sent on the Internet, his son Zhu Ang told Reuters by telephone.

The court verdict said this was a serious crime that deserved stern punishment, said Zhu Ang, who was allowed to attend the court hearing with his mother.

Now my mother is terribly upset, even if we saw this coming, said Zhu Ang, 31. He said the verdict cited his father's online calls for mobilisation in the name of democracy.

Basically, the only chance my father had to say anything was when he was being taken out after the hearing, and he stopped and said, 'I want to appeal'.

Tensions over human rights are likely to overshadow talks when Xi visits the United States next week. Vice President Joe Biden, who will host Xi, met advocates to discuss the deterioration of rights in China, the White House said on Thursday, signalling the issue is likely to figure in talks.

Xi, who is nearly certain to succeed Hu Jintao as Communist Party chief in late 2012 and as state president in early 2013, leaves on Monday for Washington. Xi (pronounced like shee) is likely to face U.S. criticism over China's clampdown in restive Tibetan areas after a series of self-immolation protests.

At a briefing on Xi's trip, a senior Chinese diplomat, Cui Tiankai, indicated his government would not welcome being publicly criticised by the Obama administration over rights.

The problem now is that internationally there are some people who always grab hold of the human rights banner when they want to speak ill of China, said Cui, a vice foreign minister. I think that this is abusing the notion of human rights.

U.S. DEEPLY CONCERNED

In Washington, U.S. State Department spokeswoman Victoria Nuland said the U.S. government was troubled by the sentence.

We are deeply concerned about these reports that he's been found guilty of inciting subversion of state power and sentenced to seven years in prison for writing a poem, Nuland told reporters at her daily briefing.

We remain, more broadly, deeply concerned about the worsening human rights situation in China, including the Chinese government's harsh sentences of human rights activists and recent violence in Tibetan areas, she added.

We call on the Chinese government to release Zhu Yufu and all others detained for exercising their rights.

China's leaders are steeling for a generational leadership handover late this year, a politically sensitive time that is likely to harden their resolve to quell dissent.

The sentencing of Zhu, who turns 59 this month, followed the jailing of two other Chinese dissidents in December who received prison terms of 9 and 10 years on subversion charges.

Zhu was jailed for two years in 2007, following a seven year jail term that started in 1999 for his outspoken activism. He was arrested again in April.

At his trial, prosecutors cited his poem, It's time, as well as text messages he sent using the Skype online chat service, his lawyer, Li Dunyong, told Reuters at the time.

There was no suggestion Skype helped police collect evidence, said Li.

It's time, Chinese people! It's time. The Square belongs to all, said the poem.

References to a square might evoke memories among many Chinese people of Tiananmen Square in Beijing, the epicentre of pro-democracy protests in 1989 that were quelled by armed troops. But the poem did not mention that.

Repeated calls to the Hangzhou Intermediate People's Court, which tried and sentenced Zhu, were not answered.

(Reporting by Chris Buckley; additional reporting by Arshad Mohammed in Washington.; Editing by Sanjeev Miglani and Todd Eastham)