US civil rights leader Al Sharpton said Thursday at a memorial for George Floyd, the African-American man whose death during an arrest set off mass protests, that it was time to hold police accountable and that his death would not be in vain.

"You changed the world George," the 65-year-old Baptist minister said at the memorial service at North Central University in Minneapolis, where Floyd died on May 25.

"This is the era to deal with policing," Sharpton said. "America, this is the time for dealing with accountability in the criminal justice system," he said.

"We won't stop," Sharpton said in a reference to the protests which have swept the country since Floyd's death. "We're going to keep going until we change the whole system of justice."