Famed Chinese dissident artist Ai Weiwei is calling on western countries to maintain pressure on China over human rights abuses. Speaking at a Council on Foreign Relations event in New York City this week, Ai said Chinese freedom of expression is suffocating under the increasingly restrictive policies of President Xi Jinping. "There is no space for political dissidents in China," he said. "If you touch any political issues, there is no such thing as rule of law." Ai, who was imprisoned for 81 days in 2011 for his outspoken views on human rights, says that even lawyers are facing jail for defending activists against wrongful accusations. "You just defend some people being wrongly accused, and you can be put in jail," Ai said. "Many of them are being falsely accused without trial; they are still in jail." Since Xi took power in 2012, China has arrested hundreds of lawyers and activists. Xia Lin, a rights lawyer who defended Ai and other activists, for example, was sentenced to 12 years in prison in September on fraud charges. Ai, who was imprisoned for criticizing the government and exposing official corruption, was required to pay substantial fines and was banned from traveling overseas for several years. In New York for a series of upcoming exhibitions, he's urging Western countries to stand up for their principles. "You have to stick to what you think is right," he said. "I think people should enjoy human rights and other values. As long as you are human, as long as we live and exist together, I always encourage people to openly discuss, to face and to confront [human rights issues]. "There is no excuse not to speak of human rights, not to defend universal values," he added, explaining that he believes that even if Western nations stopped pressuring China on human rights, Beijing would view it as a sign of diplomatic weakness. "They will only show respect for those who uphold the principles." Ai does not think, however, that the administration of President Xi Jinping alone is responsible for many of China's problems today. "Many of the problems Xi faces come from the past half century. He did not create them," Ai said. "Everything he did he must do, or he would not survive. The Control of the Internet, anti-corruption, totalitarianism, he has no choice unless he really wants to abandon the CCP [Chinese Communist Party] system, which I think is too much to ask of him." The celebrated artist has focused his efforts as a human rights activist on the Syrian refugee crisis since Christmas last year. He believes the human rights disaster in Syria is far more serious than abuses currently taking place in China. He is making a documentary film of the Syrian refugees, for which he has visited the borders of more than 10 countries and interviewed more than 100 people. A solo exhibition of his work will be on display this month at three galleries in New York City. This report was produced in collaboration with VOA's Mandarin Service.