Christian leaders have reponded angrily to the decision of a grand jury not to charge a white police officer following the death of Eric Garner in New York City.

Garner, who had been selling cigarettes on a pavement, was held in a chokehold by Officer Daniel Pantaleo despite saying at least eight times, "I can't breathe". The cry has been taken up as a slogan by protesters against the verdict.

K Marshall Williams, president of the Southern Baptist Convention's National African American Fellowship, said that the grand jury's action was an "outrageous verdict" that is "a clarion call to us to be light in the midst of so much darkness".

"I cry out to the Lord this morning, for my spirit is deeply grieved and filled with righteous indignation, as I mourn with the family of Eric Garner as they endure the pain of this visualized injustice," Williams told Baptist Press.

Russell Moore, president of the Ethics and Religious liberty Commission (ERLC) said: "I'm stunned speechless by this news. We hear a lot about the rule of law – and rightly so. But a government that can choke a man to death on video for selling cigarettes is not a government living up to a biblical definition of justice or any recognisable definition of justice."

The decision came only days after a decision not to indict Officer Darren Wilson for killing Michael Brown led to protests in Ferguson, Missouri, and in many other cities.

Moore said that African Americans – especially males – "are more likely to be arrested, more likely to be executed, more likely to be killed."

"We have to acknowledge that something is wrong with the system at this point and something has to be done," he said.

"We may not agree in this country on every particular case and situation, but it's high time we start listening to our African American brothers and sisters in this country when they tell us they are experiencing a problem.

"For those of us in Christ, we need to recognise that when one part of the body of Christ hurts, the whole body of Christ hurts. It's time for us in Christian churches to not just talk about the Gospel but live out the Gospel by tearing down these dividing walls not only by learning and listening to one another but also by standing up and speaking out for one another."

US Attorney General Eric Holder, who already has mounted a civil rights review of the Ferguson shooting, on Thursday promised a full probe of the New York case.

Pantaleo could still face disciplinary action from an internal police investigation, his lawyer said, adding that he expects that process to move quickly and that his client would be exonerated.

A departmental investigation will likely focus on whether Pantaleo employed a chokehold, banned by police department regulations, in restraining Garner as he and other officers sought to arrest him for allegedly selling cigarettes illegally on a Staten Island sidewalk in July.

In addition to triggering protests around the country, the New York and Missouri cases have re-ignited debate over a US law enforcement system widely perceived to unfairly target African Americans and other minorities.

Thousands of marchers snaked through the streets of Manhattan on Thursday night, beginning at the evening rush hour and picking up recruits along the way, often weaving between cars and trucks and bringing traffic to a near standstill.

Tensions rose as a crowd of at least 3,000 congregated in Times Square about an hour before midnight, shouting at police, "Who do you protect?" as hundreds more officers moved in to force protesters onto sidewalks. There were a number of arrests but no overt outbursts of violence.

Hours earlier, protesters parading through lower Manhattan staged sporadic sit-ins at intersections before police in riot gear warned them to move on or face arrest. Most marchers complied, and the atmosphere among the racially mixed crowd was boisterous, upbeat and mostly peaceful.

Sharon Gordon, 52, of Matawan, New Jersey, said she hoped politicians would take heed. "There's been a confluence of social media and outrage," she said. "I do believe for the first time we're about to make a change."

Subsequent waves of marchers later crossed two bridges connecting Manhattan and Brooklyn, briefly blocking traffic, then converged on Manhattan's southern tip, at the ferry terminal for Staten Island.

The main group of demonstrators headed west and briefly closed the West Side Highway, resulting in at least a handful of arrests, before turning north again through Greenwich Village and Chelsea.

A smaller crowd confronted police with taunts. Chesray Dolpha, 31, yelled at the officers: "We are not violent. We are not touching you. What are you doing with that baton, brother?" The police made eye contact but did not reply.

Thursday's rallies in New York and elsewhere were generally larger and more numerous than the previous night.

Unlike the August 9 fatal shooting of 18-year-old Michael Brown by a policeman under disputed circumstances in the St. Louissuburb of Ferguson, Missouri, Garner's encounter with New York police was captured on video that went viral online.

The clip from a bystander's mobile phone shows Pantaleo grabbing Garner from behind with his arm wrapped around Garner's throat, wrestling him to the sidewalk as three other officers helped subdue him. Garner is heard repeatedly gasping, "I can't breathe".

Pantaleo's lawyer, Stuart London, said on Thursday his client testified to the New York grand jury that he never put pressure on Garner's neck but instead used a proper takedown technique.

The city's medical examiner has said officers killed Garner by compressing his neck and chest, adding that Garner's asthma and obesity contributed to his death.

Although chokeholds are officially prohibited, the 2,000-page police patrol guide is vague about whether they are permitted under certain circumstances, said Maria Haberfeld, who heads the law and criminal justice department at John Jay College.

That grey area, she said, may have influenced the grand jury and could be a factor in the departmental probe.

New York City Mayor Bill de Blasio, who took office in January promising to improve police relations with minorities, told reporters the city's thousands of officers would undergo extensive retraining.

"The relationship between police and community has to change," he told a news conference. "People need to know that black lives and brown lives matter as much as white lives."

(Additional reporting by Reuters)