The United Nations has criticized China for what it calls “severe suppression of dissent.”

The comment came Friday from the U.N.'s Office of the High Commissioner for Human Rights. It said the crackdown appears to be a deliberate attempt to intimidate human rights defenders.

China sentenced writer and democracy activist Li Tie to 10 years in prison this week for writing a series of essays urging citizens to defend their rights. A relative of the activist says Li was found guilty of “subversion of state power.”

According to the U.N., Li is the fourth Chinese dissident since December to receive a lengthy prison sentence.

In December, Chinese courts gave a nine year prison sentence to veteran democracy activist Chen Wei and jailed fellow activist Chen Xi for 10 years after they posted online articles that the government deemed subversive.

U.S. Ambassador to Beijing Gary Locke said Monday that China's human-rights record is deteriorating in the face of pro-democracy protests in the Middle East. He said China's human-rights climate is “in a down period and it is getting worse.”

But China's foreign ministry rejected the claim. It said that Beijing respects human rights and is only arresting those in violation of Chinese law.