Around 200 protesters demonstrated in New York to denounce fresh police killings of unarmed black men, one of more than two dozen rallies planned across the United States on Tuesday.

The crowd of black, white and Latino youths held placards saying “stop police murder,” “black lives matter” and calling for justice for African American men shot dead by US officers in recent months.

They gathered in Union Square in a rally organized by the Stop Mass Incarceration Network, which campaigns to end what it calls police brutality and racially biased police practices.

Organizers say US police have shot more than 90 unarmed people since January. Parallel rallies were called in some two dozen other cities, including Los Angeles and Chicago, they said.

On Monday, a white volunteer deputy sheriff in Oklahoma was charged with manslaughter for shooting dead Eric Harris, 44, on April 2.

Last week, a South Carolina police officer was charged with murder after being filmed on video killing Walter Scott, an apparently unarmed black man, after a routine traffic stop.

The cellphone video, from April 4, shows the officer firing eight times as Scott was running away.

A series of killings last year of unarmed black men by largely white police officers sparked nationwide protests, charges of racism and revived the debate about excessive use of police force.

The demonstrations were galvanized by the August 2014 killing of 18-year-old Michael Brown in Ferguson, Missouri in bitterly disputed circumstances. The officer involved was not charged.