Eight Christian counsellors will go on trial in Nepal this week in the first religious freedom case since the country's new constitution was implemented in 2015.

The Christians were arrested for proselytising – outlawed in the new constitution – after distributing a pamphlet about Jesus in a Christian school while helping children through the trauma of last year's major earthquake in the country.

There have been reports that members of the group were tortured by the authorities.

The seven men and one woman were reportedly working for the organisation Teach Nepal when they distributed the material in the school, which is Christian but does not exclusively teach Christian children. The head of Teach Nepal, Barnabas Shrestha said the group were "invited by a pastor to do the counselling in the school," adding that the police "wanted our people to say yes, they have preached the Gospel ...which is not true".

The group is reportedly alleged to have violated Article 26, paragraph 3, of the Constitution of Nepal, which regulates religious freedom and states that "no person shall act or make others act in a manner which is contrary to public health, decency and morality, or...convert a person of one religion to another religion".

World Watch Monitor said: "The freedom of Nepal's Christians is increasingly under threat."

According to a missionary in Nepal, the Government last week announced to all leaders of Christian orphanages and boarding schools in Kathmandu that it would close them down, impose large fines and confiscate possessions if just one Christian booklet was found in their institution. It was also announced that attending a Bible club or praying with children were banned.

Further, an anonymous source told World Watch Monitor that the Social Welfare Council, which approves foreign aid for various programmes, has stopped granting approval for Christian ones.

In 2015, Nepal's Constituent Assembly voted to remain secular and resisted pressure from Hindu nationalists to become a Hindu state. Hours later, two churches were bombed.

Pamphlets promoting Hindu nationalism were found at the churches and the nationalist group, Hindu Morcha Nepal, issued a statement to the media calling for Christian leaders to leave the country and for converts to Christianity to return to Hinduism.

The eight counsellors remain on bail awaiting trial, expected to be held on Friday.