A Christian pastor who has been imprisoned in Vietnam since 2011 for the 'crime' of evangelisation has suffered torture and solitary confinement since reporting how he is being treated behind bars to US officials.

Pastor Nguyen Cong Chinh has had shards of glass into his food, has been beaten and put in stocks and been held alone and in a cramped cell.

His wife Tran Thi Hong has revealed that last month, Chinh gave officials from the US Consulate in Ho Chi Minh city details of how he had been treated in Xuan Loc Prison in Dong Nai Province, the third prison in which he has been held.

After visiting her husband on June 7, she said her husband had been advised by prison officers not to say anything to the diplomatic delegation but he disobeyed, according to UCA News. 'He told the delegation his experiences of torture, threats and mistreatment that he has endured over six years,' she said. 

'I am very concerned about his poor health in solitary confinement because he is suffering severe sinusitis and high blood pressure,' said Hong, who was herself tortured, beaten and questioned at a police station for two months after she met with a US delegation on religious freedom in March 2016 in Pleiku city.

Chinh was sentenced to 11 years in 2011 for providing religious activities to ethnic groups in the Central Highlands and is one of 83 prisoners of religious freedom in Vietnam.

The couple have four children. 

Hong recently revealed in an interview that her husband had been told by security officials that she had been engaging in an extramarital affair.

'I was shocked when my husband said on May 11 that public security officials from Hanoi came to the camp and told him that I had been unfaithful. The officials asked him, "Don't you know anything about your wife?" and said "She is committing adultery with a man."' This was nothing but lies, she added.

WATCH: Jackie Wolcott from the US Commission on International Religious Freedom advocating on behalf of Pastor Nguyen Cong Chinh and his wife.