Release International is warning about the appalling conditions in that country's jails following the sentencing this week of a pregnant British woman to life imprisonment in Laos.

Samantha Orobator, 20, was jailed for life on Wednesday in the capital Vientiane for drug smuggling. She escaped execution because she became pregnant in custody. Under an agreement with Britain she could be transferred to a British jail and serve her sentence in the UK.

Ex-prisoners from Laos tell their stories on a new documentary by Release: Enemies of the State?. They describe being held with their feet in stocks and forced to lie in their own excrement. They spoke of being beaten unconscious. Hunger and sickness were widespread and many needed medical treatment after being released.

"Samantha should be returned to the UK immediately for her and her baby's sake," said Release. "Our interviews with former prisoners from Laos reveal appalling conditions in jail."

Release travelled to Laos to investigate the treatment of Christian prisoners. They uncovered a catalogue of abuse. Several had been imprisoned without trial. They include Stephen, whose real name cannot be given for security reasons, who was arrested and jailed after a village head man objected to him talking about his faith.

He told Release: "The police put my feet in stocks and chains on my hands. I could not move. The cell smelled like a toilet. Sometimes I could not breathe because of the smell."

Pastor Timothy, whose real name has been concealed for security reasons, was arrested for bringing a foreign religion to Laos. He claims to have been beaten almost to death.

He told Release: "They asked me to sign a piece of paper that said that I would not be a Christian because Christians are not good or not right for the Lao people. I didn't sign it because of my faith."

Christians in Laos are under surveillance. Pastor Silas, whose real name cannot be given for security reasons, had previously been jailed three times for his Christian activities. Undeterred, he went to a village to talk about his faith. But the authorities were watching him. He was arrested and thrown in jail without trial.

Abigail, whose real name cannot be given for security reasons, looks after her husband's church. Her pastor husband was murdered for setting up churches. She says if she could catch up with her husband's killer she would tell him she forgives him.

She said: "The reason I believe my husband was killed was because he served God. But I would tell [his killer] I love him, because God loves him too and God will forgive him."

The Laotian constitution provides for religious freedom and bans religious persecution. Yet at a local level the authorities maintain firm control over religious activity and harass religious minorities.

Religious groups must gain state approval for evangelism, printing religious literature, and owning or building places of worship. Christians report having been forced at gunpoint to renounce their faith, while others have had their property seized.

The communist state openly encourages Buddhism and Buddhist organisations, but regards Christianity as a threat to national unity. Christians refusing to take part in state-organised religious events are seen as seditious and evangelists have been charged with treason. Release is working with its partners in Laos to support persecuted Christians.

Through its international network of missions Release supports Christians imprisoned for their faith and their families in 30 nations. It supports church workers, pastors and their families, and provides training, Bibles, Christian literature and broadcasts.

Release: Enemies of the State? is available from www.releaseinternational.org