A group of black ministers has expressed indignation at Georgia Gov. Nathan Deal for vetoing a religious liberty bill, saying he has turned his back on religious organisations.

In vetoing HB 757, Deal claimed he did not actually have any objection to the Pastor Protection Act that was passed by the House of Representatives.

"The other versions of the bill, however, contained language that could give rise to state-sanctioned discrimination. I did have problems with that and made my concerns known as did many other individuals and organisations, including some within the faith-based community," he said in a statement.

HB 757 will allow ministers, clerics and religious practitioners to refuse to perform same-sex marriage and allow people to refuse to attend such ceremonies.

It will also allow faith-based organisations to refuse to rent, lease or grant permission for property to be used for an event that violates their religious beliefs.

The bill provides that faith-based organisations should not be required to provide social, educational, or charitable services if they violate their sincerely held religious beliefs.

Former Atlanta Fire Department chief Kelvin Cochran, who was fired in 2015 for his stance on same-sex marriage, joined the pastors in their protest.

Pastor Garland Hunt, senior pastor at The Father's House in Norcross, Georgia, said, "We were totally, highly offended and angered to hear that the governor turned his back on faith-based organisations, the faith-based leadership in the state," CBN News reported.

Hunt said they met with the governor several times "and he promised us that he would sign legislation that was basically similar to what was presented to him so we feel like he didn't keep his word."

The group of pastors said they held a press conference to show that there's a group of African-American pastors who are opposed to the governor's decision to veto the bill.

"We love the Lord and we're going to stand for our religious freedom and we love our religious freedom just as much as anybody else," they said.

"So for that reason we just decided that a few of us needed to talk specifically out of our African-American tradition, understanding what we've been through, through discrimination, certainly we understand that but this is not discrimination," they said.

The religious leaders are urging the legislature to override the governor's veto.