A group of Canadian volunteers was prevented from entering the US to clean up storm-damaged homes because border guards feared they would be taking American jobs.
The 12-strong team from the Rehoboth United Reformed Church in Hamilton, Ontario, had planned to help neighbourhoods in New Jersey which remain affected by 2012's Hurricane Sandy.
The group's leader, Erik Hoeksema, admitted he had failed to ensure documents explaining the visit were sent ahead of his arrival.
But he told CBC News he managed to have two letters faxed from the American church that was hosting them, making it clear that they were there for "neighbourhood cleanups".
The volunteers were nonetheless denied entry to the US.
A spokesman for US Customs and Border Protection (CBP) stressed that "visitors intending to perform work for humanitarian purposes must provide documentation in advance to the port where they are seeking admission to the US".
In a Facebook post, Mr Hoeksema said: "This is an unfortunate incident, and the sad part is we're not the ones who lose in this. The (American) people who we were going to help miss out. As is always the case, it's the poorest neighbourhoods that have to suffer."
Below his post he shared a message from Seth Kaper-Dale, the pastor of the Reformed Church of Highland Park in New Jersey, where Mr Hoeksema's group was heading.
Mr Kaper-Dale claimed the Canadians were told that "by coming here they were stealing American jobs".
In a later post Mr Hoeksema said the border guards had been "kind".
The CBP spokesman told The Independent: "[CBP's] primary mission is to prevent the entry of terrorists and their weapons into the US, while facilitating the legitimate flow of trade and travel over the border.
"CBP is also responsible for enforcing US laws and regulations that safeguard American industry, including laws that restrict employment of foreign visitors.
"International visitors intending to perform work for humanitarian purposes must provide documentation in advance to the port where they are seeking admission to the US.
"That should include a letter from the municipality stating what the arriving group will be doing.
"In this case, CBP attempted to assist the group, but ultimately the group was unable to obtain the proper documentation to support this visit."