Leaders of some of the biggest churches in the United States have protested to Hillary Clinton over her views on abortion, expressing "deep concern".

More than 20 national African American leaders, including bishops of influential black churches, delivered a letter to Clinton expressing their frustrations over her stance on abortion, along with her positions on their First Amendment right to religious freedom.

Abortion, they say in the letter, disproportionately impacts the black community.

They also say that religion is what has historically held the African American community together.

They are "deeply troubled" by Clinton's policy positions that they see as eroding their First Amendment rights.

Their protest comes just days after Carl Anderson, Supreme Knight of the Knights of Columbus, a Christian charity that raises funds to help those in need, said that if America's politicians had the courage to act on the consensus that already exists on the issue of abortion, the number of abortions in the United States could be greatly reduced.

The letter, delivered yesterday to Clinton campaign headquarters in Brooklyn, New York, was delivered by Dr Jacqueline C Rivers, a Harvard-trained sociologist who has lived and worked among the urban poor for thirty years and is currently executive director of the Seymour Institute for Black Church and Policy Studies in Boston.

Signatories included Bishop Frank Madison Reid III, chairman of the social justice committee of the African Methodist Episcopal Church.

They called for a meeting with Clinton "to discuss some of the critical issues in the black community: education and employment, religious freedom, violence, and justice for the unborn."

Rivers said these topics are of great importance to the 41 million blacks in the nation but have largely been absent from the presidential debates. Nearly eight in 10 African Americans belong to one of the country's black churches.

They complained in particular that in April 2015 in a speech before the National Organization of Women, Clinton stated: "Deep-seated cultural codes, religious beliefs and structural biases have to be changed."

The church leaders say that for political leaders to call for changes in citizens' beliefs constitutes a denial of religious freedom.

They state: "Today in the United States more than ten million people of African descent face a crisis of catastrophic proportions. Life in our major post-industrial centers can be poor, nasty, brutish and short. When it comes to the black underclass America's two major political parties appear to have achieved a rare unity in their record of bipartisan indifference."

They reiterate that the vast majority of black churches hold to biblical teaching.

"Abortion is the deliberate destruction of a human life in its most vulnerable state. Biblical principle and natural law, both of which prohibit the taking of innocent human life, compel our concern about the increasing moral complicity with abortion."

Nationally in the US, there are 365 black babies aborted for every 1,000 that are born.

Blacks account for roughly 38 per cent of all abortions in the country although they represent just 13 per cent of the population.

In New York City in 2013 there were more abortions among black women in the city, more than 29,000, than there were black babies born.

On religious freedom they continue: "The drive to normalize immoral sexual behavior has inspired some to dishonor the memory of courageous blacks who experienced the unique horrors of white supremacy, slavery, rape, terrorism and apartheid in the US."

They criticise politicians "who seek to criminalize our biblical texts as hate speech."

They ask Clinton in the letter: "What would you do as president to guarantee that religious freedoms are balanced against civil rights rather than being trumped by them?"