Dozens of Vietnamese pastors who refused to comply with government orders to consolidate their unregistered house churches into a single, officially approved church have been imprisoned for their faith and are at risk of being poisoned.

According to a report from Christian Aid Mission, at least 108 pastors are currently imprisoned because they refused to register or combine their churches despite pressure from local officials. Churches regulated by the government are prohibited from meeting in smaller groups: no Sunday school classes for children or adults, no youth groups or other gatherings apart from the congregational worship as a whole.

In addition, taking Communion and collecting offerings are forbidden, police monitor sermons to ensure nothing is said against communism, and plural leadership is prohibited; only one leader is allowed for each congregation. Children are also prohibited from learning about Jesus Christ except for in the privacy of their homes.

"The government wants to combine them to limit their growth and have more control," a ministry leader known as "Su" told the outlet. "If the pastors refused to sign a paper saying they would combine and that their gatherings would not go over 500 people, they would be beaten or thrown into prison."

In the Gia Lai Province, authorities forced 12,000 Christians in 20 unregistered churches to combine at a single facility accommodating 1,600 people, Su said. Rather than imprison those who resisted, however, authorities in Gia Lai Province imposed fines.

"Last Easter, each church that refused to combine congregations into the one registered church was fined $60," he said, an amount more than half the average monthly income of many Highland tribal people.

While in prison, pastors are subject to torture and harsh conditions. Failure to comply with all orders and regulations can bring lethal retribution, said Su, who was nearly killed himself while spending a total of seven years and two months in prison between 1975 and 1985.

"If you do not strictly follow the rules, they can put poison in your food," he said. "So you take a little bit, and if you feel something or want to vomit, you stop eating. A few people have died."

The 2016 World Watch List, a ranking from Open Doors of the countries that most persecute Christians, put Vietnam at No. 20, and gave the Communist country the maximum score in the violence category. Christians make up just 9.5% of the country's population of 92.7 million.

Despite the government's continued crackdown on Christianity, Su's ministry team has continued to go to several areas to proclaim Christ and train church leaders. There are 22 tribes in the Central Highlands that have no strong Christian presence, and the ministry has reached out to 10 of them, he said.

In an effort to evangelize the rural areas, the ministry sends 10 new Christians at a time from various villages to its urban base for training several times per year, then sends them back to their communities to spread the gospel.

"This keeps the local police from knowing what they were doing and where to intercept them," Su said.

Evangelistic Bible studies rotate to different village homes to keep local authorities from finding out about them, he added. The ministry also arranges for converts from one tribe to reach out to a nearby tribe.

"They know each other as neighbors, and they may speak different languages but understand each other well enough to communicate," Su said.

To learn more about Christian Aid Mission or to donate, visit their website.