Thousands March Against US Police Killings

Tens of thousands of demonstrators have taken to the streets of cities across the US to protest at the killings of unarmed black men by police and call on politicians to act.

Organisers expected the rallies to be among the largest seen over the lethal actions of officers in New York, Cleveland and Ferguson, Missouri.

Protesters in Washington carried placards reading "Black Lives Matter" and "Who do you protect? Who do you serve".

Marchers shouted "No justice, no peace, no racist police" and "Hands up, don't shoot".

Among those who took part in the march on the Capitol Building were the families of Eric Garner, killed by an officer using a chokehold position in New York, Michael Brown, who was fatally shot in Ferguson, Trayvon Martin, who was shot by a neighbourhood watch volunteer in Florida, and Tamir Rice, who was fatally shot in Cleveland, Ohio.

Esaw Garner, the widow of the 43-year-old, who died in July after officers arrested him in Staten Island on suspicion of selling loose, untaxed cigarettes, told marchers: "Let's keep it strong, long and meaningful."

"Wow, what a sea of people," said Mr Brown's mother, Lesley McSpadden.

"If they don't see this and make a change, I don't know what we're going to do."

The lack of criminal charges brought by grand juries in the New York and Ferguson cases has fuelled protests across the US.

Civil rights leader the Rev Al Sharpton, whose National Action Alliance headed the Washington protest, said in a statement: "We need more than just talk - we need legislative action that will shift things both on the books and in the streets."

He called for legislation that would allow federal prosecutors to take over cases involving police.

Local prosecutors who work with police regularly and then must investigate officers faced a conflict of interest, he argued.

Protesters in Washington were expected to arrive by bus from as far away as Florida, Connecticut and Pittsburgh.

Organisers estimated the crowd at 40,000 to 50,000.

The rally blocked Pennsylvania Avenue between the White House and the US Capitol.

The march in New York, a city which has seen a series of protests after a grand jury failed to indict the officer who killed Mr Garner, was estimated by observers to have drawn a crowd of more than 10,000.

The crowd headed north up Manhattan's Fifth Avenue from Washington Square Park and was due to end at the city's police headquarters.

Some chanted "How do you spell racist? NYPD" and some taunted police guarding the route.

New York march co-organiser Umaara Elliott said in a statement: "It's open season on black people now.

"So we demand that action be taken at every level of government to ensure that these racist killings by the police cease."

Hundreds of protesters also gathered in Boston, Massachusetts.

The state police said "several demonstrators who failed to comply with the law despite orders to do so have been taken into custody".