The three lawyers were all picked up in July 2015 as part of an unprecedented campaign called the "709 crackdown," during which the country's security forces arrested, sentenced or questioned hundreds of legal staff and activists.
Xie recently informed his lawyers of the inhumane methods interrogators used to force him to confess to inciting subversion of state power and testify against other lawyers. Beatings, extreme sleep deprivation, humiliation and threats to harm to his family are among them.
"I'm going to torment you until you go insane," one captor reportedly told Xie in the beginning of the interrogation session. "Don't even imagine that you'll be able to walk out of here and continue being a lawyer. You're going to be a cripple."
According to the China Human Rights Lawyers Concern Group, Li and Wang also experienced similar severe mistreatment, including electric shocks.
"If verified, this mistreatment would amount to torture," the EU's foreign affairs spokesperson said in a statement. "All necessary measures to ensure the safety and wellbeing of these individuals need to be taken."
Rights groups say forced confessions are a common practice in China. The United Nations' Committee Against Torture's said in the December 2015 review of the country that it was disturbed by reports of torture and ill-treatment in the mainland's justice system.
The EU applauded the release of two other rights defenders caught up in the 709 crackdown, Xie Yanyi and Li Chunfu. Li, who spent more than 500 days in detention, has since been diagnosed with schizophrenia.