A Christian pastor is still languishing in jail in China after he was arrested almost two years ago on espionage charges.

Pastor Li Guozhi, alias Yang Hua, the vicar who used to be in charge of the Huoshi Church in Guizhou province, has developed a serious liver disease while incarcerated and his health condition continues to deteriorate, the Express reported, quoting his lawyers.

Lawyers Chen Jiangang and Zhao Yonglin, who recently visited the Christian pastor, said Hua is currently "suffering from serious health conditions and is suffering from liver pain along with various other serious diseases." They also maintained that the vicar is being subjected to "inhumane" conditions while in prison.

Pastor Hua was taken into custody by Chinese authorities in December 2015 after he refused to give the police a hard drive belonging to his church. He was subsequently charged for allegedly "divulging state secrets."

Despite his frail condition, Pastor Hua is still being tortured by Chinese prosecutors, who are trying to force out a confession from him, his lawyers revealed.

"Prosecutors visited him twice, applied pressure to his feet, and repeatedly threatened to kill him and harm his family members if he failed to confess his supposed crimes," the lawyers said.

They said they are planning to sue the Chinese prosecutors for allegedly "using torture to extort a confession," although this might further delay Pastor Hua's trial.

It was also recently revealed to the lawyers that the vicar's wife, Wang Hongwu, has been put under surveillance by Chinese authorities.

Wang said Chinese police officers are keeping watch on her house round-the-clock, with state agents even sleeping in cars near her home.

"They wanted to check the identity cards of friends that came to my house. I said, 'Why are you checking my friends' identity cards? Is it illegal to come to my house?'" Wang said, as quoted also by Express.

The persecution of Pastor Hua and his family is only the latest indication of the Chinese Communist Party's tighter grip on religious practices in the mainland. At present, there is an existing ban on singing Christian songs in public, while strict travel restrictions have been imposed on religious workers going to China.