A man who donated to a group fighting against the amendment of Minnesota’s marriage equality ban has asked his contribution to remain anonymous over fears that his Catholic employer may fire him.

The man gave $600 to Minnesota United for All Families.

The financial board of the Minnesota UFAF said that the man, now known only as John Doe, could lose his job if his donation became publicly known.

He was granted anonymity on 7 August, as reported in the Minneapolis-St Paul Star-Tribune.

Minnesota United for All Families said in a statement: “Mr. Doe argues that because his job requires him to represent the Catholic organisation’s positions to others from time to time, if his opposition to the marriage amendment was known, it would cause immense strain in his working relationships.

“Mr. Doe believes that this strain may be enough that his employment would be terminated.”

The Catholic Church has strongly supported the amendment, raising funds for the campaign to support it.

In January, Johh C. Nienstedt, the archbishop of St. Paul and Minneapolis declared that priests must take a position on the matter or remain silent.

Minnesota already bans gay marriage but anti-gay campaigners say a constitutional amendment is needed to protect the ban. Voters will decide the issue in November.