The charity, Open Doors UK & Ireland says Christian families in Vietnam are being excluded from receiving help from local authorities because of their faith.
Six Christian families in the north of the country have reported that they were refused water tanks as part of a government initiative to help villagers store rainwater.
A pastor from the area says that when they were distributing the tanks, local officials told them: "You are Christians, we have no responsibility for you. Go, ask your church to help you.
"If you want to receive the aid, return to our culture, and worship our ancestors again. If you won't, then do not expect to receive anything."
The scheme from the Vietnamese government to provide water tanks to families living in a province near the border with China was announced in June this year.
The mountainous area means that drawing groundwater is difficult. Rainwater is the main source of water for residents but storing it has proven problematic.
The government, therefore, pledged to provide each family with 10m Vietnamese Dong, about £313, to build tanks.
But the snub from local officials means that when the dry season comes, they must walk six hours to fetch water from their nearest river.
Dr. David Landrum, Director of Advocacy at Open Doors, said: "This is typical of how local authorities in Vietnam treat some Christians.
"We know from our research that Christian communities in the Central Highlands of Vietnam, many of them from the ethnic minorities, are neglected economically and socially.
"There have been many cases where Christians have been excluded from several government relief programs by local authorities - even from COVID-19 aid distribution.
"It is unacceptable - not least when the central government has said that all families in the area should be given water tanks to help them gather rainwater.
"The residents in this northern province of Vietnam are poor and just getting food on their tables is difficult. Spending money to build tanks themselves is beyond their capacity."