A number of Christians were beaten and arrested by Vietnamese government officials after they refused to renounce their faith and worship a Buddha statue, a pastor has revealed.

Pastor Hoang Van Pa told persecution watchdog group International Christian Concern that government officials threatened 33 Hmong Protestants in Phá Lóm village in November if they refused to renounce their Christian faith.

Police reportedly gathered personal information about the Christians and then carried out an open trial before the community. Presenting an image of the Buddha, police tried to force the Christians to abandon their faith and worship the statue instead.

Four of the Christians were subsequently arrested and beaten, and government officials continued to harass Protestants in several other raids throughout November and December.

Hmong Christians are estimated to make up 300,000 of the one million Hmong people in Vietnam. Over the last 30 years, increasing numbers of Hmong have converted to Christianity from the group's traditional religion of animism (belief in the spirit world and the interconnectedness of all living things).

These tribal groups "experience the most intense persecution" according to religious freedom watchdog group Open Doors, which ranked Vietnam among the top 50 countries where Christian persecution is most severe.

As Dzung, the representative of the Interdisciplinary Inspection Team, explained that Vietnam has banned the Protestant Christian faith. Those who refuse to renounce their faith are expelled.

ICC notes that last year alone, more than 100 believers were expelled from Yen Bai province and Lao Cai province. They had to find their own way to flee to nearby Thailand, where they have the prospect of applying for refugee status.

"Due to its ethnic background and high percentage of practicing Christians, Vietnam's Hmong community is often targeted and harassed by both the government and neighboring communities," wrote ICC's Regional Manager Gina Goh.

"In a Communist country where Christianity is often seen as unpatriotic or a threat to the regime, Hmong Christians constantly face discrimination, harassment, land grabs, torture, and imprisonment."

Last year, two dozen Hmong Christians in Vietnam refused to recant their faith, prompting a mob to attack them. According to the Vietnam Committee on Human Rights (VCHR), four of the Christians were hospitalized with injuries to the head and arms.

"Such attacks and acts of harassment against religious communities have multiplied recently in Vietnam," VCHR noted in a statement. "The authorities are invoking the law to criminalize legitimate religious activities, creating a climate of impunity for a wide range of violations of freedom of religion or belief."

ICC has warned that the persecution of Hmong Christians is expected to continue in 2019 and urged the international Christian community to lift them up in prayer.