ALTAY, China — A university professor who has become the most visible symbol of peaceful resistance by ethnic Uighurs to Chinese policies was sentenced to life in prison on Tuesday after being found guilty of separatism by court officials in the western region of Xinjiang, which Uighurs consider their homeland.

The punishment handed down to Ilham Tohti was the harshest that Chinese officials have imposed on a political dissident in recent years. Mr. Tohti was convicted after a two-day trial in Urumqi, the regional capital, that ended last Wednesday. He was taken by the police last January from his home in Beijing, where he teaches economics at Minzu University, and brought to Xinjiang, where he was charged with separatism.

“It’s not just! It’s not just!” he yelled as police officers dragged him from the courtroom, his lawyer, Li Fangping, said.

Officials in Xinjiang are grappling with a surge in violence between the mostly Muslim, Turkic-speaking Uighurs and the Han, the dominant ethnic group in China. Communist Party leaders have long said that Xinjiang is in a battle with the forces of terrorism, separatism and religious extremism, and that all steps must be taken to stamp out the insurgency.

But foreign scholars, diplomats and human rights advocates denounce China’s hard-line policies against the Uighurs, and say the harsh measures that China has taken against moderates like Mr. Tohti will only lead to further radicalization of Uighurs and a rise in violence, including the kind encouraged by foreign jihadist groups.

Mr. Tohti, 44, was charged with organizing and leading a separatist group, Mr. Li, the lawyer, said in a telephone interview. As evidence, officials presented in court material representing Mr. Tohti’s viewpoints on Uighur identity and China’s ethnic policies, much of it drawn from his classroom teachings and the website he ran from late 2005 to 2008, Uighur Online. Officials argued that Mr. Tohti’s separatist group included seven of his students, who have also been detained and will almost certainly be tried, Mr. Li said.

Among prosecutors’ arguments was that Mr. Tohti had “internationalized” the Uighur issue by giving interviews to foreign reporters and had translated foreign articles and essays about Xinjiang to be posted on Uighur Online.

“He showed great spirit in court,” Mr. Li said. “He gave an eloquent defense to every accusation. He maintained his innocence from the beginning to the end. He gave a brilliant 90-minute defense speech at the end of the trial.”

Mr. Li added: “I hate to think about his wife and two young sons. Tohti’s wife is barely coping. They just had their entire life’s savings of 800,000 renminbi frozen,” an amount equal to $130,000. “How will they live on? How is she going to raise two children all by herself? This family’s tragedy has only begun.”

The Chinese authorities had previously frozen Mr. Tohti’s bank account, ostensibly to investigate the sources of the money. On Tuesday, the court ordered the confiscation of all of his assets.

Mr. Tohti has two sons, ages 5 and 8, who live in Beijing with his wife.

In an emotional telephone interview on Monday night, Ms. Guzelnur said she had not expected the charges to be so harsh and that she had yet to tell her sons about their father’s plight. “I will tell them what happened when they grow up,” she said.

She added: “I’m not worried about my husband’s spirit. It’s his health I worry about. He has heart problems and bad lungs.

“No matter what happens, I will wait for him to come home,” she said. “We will wait forever.”

Mr. Tohti has a daughter from an earlier relationship, Jewher Ilham, who is attending Indiana University in Bloomington, where Mr. Tohti was to have taken up a post as a visiting scholar before the Chinese police prevented him from boarding a plane with Ms. Ilham in February 2013.

The police intensified their scrutiny and harassment of Mr. Tohti after a car crash in October 2013 that killed and injured tourists near Tiananmen Square; Chinese officials said the crash was the work of hostile Uighurs. The police actions culminated in the detention of Mr. Tohti in January.

For years, officials in Xinjiang had been intent on silencing Mr. Tohti, despite the fact that he lived outside of the region, in Beijing, and the Xinjiang government appeared to have been given permission by the central authorities to make its move in 2013, Mr. Tohti’s associates say.

Xinhua, the Chinese state news agency, said in an English-language report Tuesday afternoon that the ruling declared Mr. Tohti had “bewitched and coerced young ethnic students” into working on his website and that he had “built a criminal syndicate.”

Foreign governments have condemned China for its treatment of Mr. Tohti. Several Western nations tried sending diplomats to the trial, but they were turned away at the courthouse, which was heavily guarded by police officers, some carrying riot shields. Foreign journalists were also barred from attending the trial.

“Professor Tohti has consistently supported human rights for China’s ethnic Uighur citizens,” a spokesman for the United States Embassy in Beijing said during the trial. “His arrest silenced an important Uighur voice that peacefully promoted harmony and understanding among China’s ethnic groups, particularly Uighurs. We stress the importance of Chinese authorities differentiating between peaceful dissent and violent extremism.”

The United States government has called on China to release Mr. Tohti and the seven students who have been detained.

The PEN American Center, which campaigns for freedom of expression and gave Mr. Tohti an award in March 2014, three months after he had been detained, released a statement Tuesday that said, “His conviction makes a mockery of China’s professed commitment to social harmony by silencing one of the country’s unifying voices and, with it, fellow Uighur writers who are now unlikely to dare speak out.”

Maya Wang, a researcher for Human Rights Watch, said she could not recall any ethnic Han advocates or dissidents receiving a life sentence in recent years. But she said the authorities usually treat dissent by Uighurs much more harshly, especially following ethnic rioting in Urumqi in 2009 that resulted in the deaths of at least 200 people, most of them Han. A Uighur radio journalist, Memetjan Abdulla, was sentenced to life in prison in 2010.

Ms. Wang noted that the indictment of Mr. Tohti was consistent with a broad move in recent years by the Communist Party to silence advocates known for their “measured words and actions,” including Xu Zhiyong and Pu Zhiqiang, two well-known lawyers arrested for their political activities.

“These and Tohti’s harsh sentence are signs of just how far the authorities have gone in severely restricting the already limited civil liberties in China,” she said, “and that the situation might get even worse down the road.”