Washington: The US on Friday renewed calls for China to release jailed dissident Liu Xiaobo who won last year's Nobel peace prize.

"A year after the Nobel Peace Prize, he is still in jail. Three years after he was sentenced, he is still in jail," State Department spokesperson Victoria Nuland told reporters in a conference.

She also asked China to stop harassing his wife, "And not only that, Chinese authorities are harassing and holding under house arrest his wife. So thank you for the opportunity to renew our call to the Chinese Government to release him and to stop harassing his wife and to uphold China's international human rights obligations," Nuland said in response to a question.

The United States always raise the case of continued imprisonment of Liu every time its officials talk about human rights with the Chinese, she said.

"Human right is part of our regular dialogue with China. It's not always an easy conversation, but we will keep having it," Nuland said.