A Beijing court on Sunday sentenced a legal scholar and founder of a social movement to four years in prison for disrupting order in public places, a case that the U.S. government and other critics say is retribution for his push to fight corruption and create equal educational opportunities.

Amid tight security, the Beijing No. 1 Intermediate People's Court handed down the verdict against Xu Zhiyong, founder of the loosely knit New Citizens movement, in a blow to the group and China's rights activism.

Hundreds of police officers — both in uniform and in plainclothes — were stationed around the courthouse. They pushed away foreign journalists and took away Xu's lawyer when he attempted to speak to the media, but not before he denounced the process as "very unfair."

Xu told "the court that the last shred of dignity of China's rule of law was destroyed today," lawyer Zhang Qingfang said before he was escorted away by police and shoved into a police van.

Xu's prosecution is part of a broader crackdown since last spring on dissent, including the silencing and detentions of influential bloggers and advocates for minority rights in Tibetan and Muslim Uighur areas.

Earlier this month, the authorities took away Ilham Tohti, a Uighur scholar and outspoken critic of China's ethnic policies. A police statement accused the university professor of separatism, inciting ethnic hatred and advocating violence to oppose China's rule over the far west region of Xinjiang, home to the ethnic minority of Turkic-speaking Muslim Uighurs.

Xu's verdict drew widespread criticism, with U.S. State Department spokeswoman Jen Psaki saying in a statement that the U.S. was "deeply disappointed" and that Beijing should release Xu.

Amnesty International called the imprisonment a travesty and Human Rights Watch said convicting Xu "makes a mockery" of Chinese President Xi Jinping's crusade against corruption.

The ruling Communist Party is wary of any form of social force such as Xu's New Citizens movement because of its potential to threaten the party's rule at the grassroots level. Several other activists have stood trial or are scheduled to appear in court — all on the same charge of disrupting public order.

Xu and his followers purposely kept the movement unstructured so as not to challenge the party's zero intolerance on organized movements. They downplayed any political appeals and championed causes that were in line with the party's own stated goals.

Still, Xu's fledgling campaign became a target after it inspired people across the country to gather for dinner parties to discuss social issues and occasionally to unfurl banners in public places in small rallies.

Reflecting the sensitivity with which authorities view the case, police on Sunday pushed foreign journalists back from an ever-expanding zone around the courthouse, and took press credentials away from some of them.

Zhang said later the police released him after they observed foreign journalists leaving the area.

European diplomats also called on Chinese authorities to release Xu immediately.

Raphael Droszewski, first secretary of the European Union delegation to China, said the case has "heightened our concern at the situation being faced by a number of Chinese human rights defenders who have been prosecuted in relation to peaceful action against corruption and public advocacy of the law, transparency and social justice."

Xu's trial was held Wednesday in Beijing, just hours after a U.S.-based journalism group released a report linking relatives of Xi and other political leaders to offshore tax havens, renewing allegations that the communist elite has benefited from China's economic boom and hidden the proceeds overseas.