Britain's poorest families, including 7.5 million children, are at risk of further difficulty unless the government protects them from an expected rise in inflation, four of the UK's major Churches warned today.

Ahead of the unveiling of the government's Autumn Statement on Wednesday, the Baptist Union of Great Britain, the Church of Scotland, the Methodist Church and the United Reformed Church have released a joint statement calling on the Chancellor of the Exchequer to care for families on benefits.

In January, parliament voted to freeze most working age benefits in cash terms for the next four years.

This means their value will be "eroded by inflation year on year... [and] will cut the level of the support available to more than four million families containing at least 7.5 million children," the Churches said.

"The benefits freeze is putting the poorest in the way of economic harm," said Rachel Lampard, vice president of the Methodist Conference.

"In January, when parliament voted to freeze benefits, inflation was low, stable and predicted to remain low. Today the economic outlook is very different.

"Rising inflation will mean 7.5 million children will be hit by cuts harder and faster than was ever intended. It is time this huge cut was brought under control."

The prices of basic goods including food are likely to be the first to rise as a result of the fall in value of the pound, the Bank of England has predicted.

Rev Dr Richard Frazer, convener of the Church and Society Council of the Church of Scotland, warned: "Many parents are already going without to ensure their children are fed."

He said: "The cost of food is rising and more and more do not have enough to eat. A decent welfare system must ensure that is not the case. Benefits need to keep pace with the rise of food costs."

Rev Stephen Keyworth, faith and society team leader of the Baptist Union of Great Britain, added: "There are already record numbers of people seeking emergency help from food banks and church-run night shelters are seeing increasing demand.

"If the benefit system is to do its job of supporting families through difficult times there must be a link between the price of food and shelter and the value of benefits.

"The alternative is more hunger and more ill health. We must not let people's God-given potential to be allowed to go to waste because of poverty."