WASHINGTON (AFP) - Democratic presidential nominee Hillary Clinton postponed a visit to Charlotte, North Carolina on Friday (Sept 23) after the city's mayor asked both major candidates to delay visits, her campaign announced.

Earlier in the day, the campaign said Clinton would visit the city on Sunday after the police shooting of an African-American man triggered days of unrest.

"After further discussion with community leaders, we have decided to postpone Sunday's trip as to not impact the city's resources," the campaign said in a statement. "She will plan to visit Charlotte next Sunday, provided circumstances allow."

Charlotte Mayor Jennifer Roberts had earlier asked Clinton and her Republican White House rival Donald Trump to delay visits, citing "very stretched resources for security."

Keith Lamont Scott's death on Tuesday is the latest in a string of police-involved killings of black men that have fueled outrage across America.

Charlotte has been rocked by three nights of violence-marred protests, prompting the governor to declare a state of emergency in the southern US city.

Hundreds of protesters were out again on Friday night calling for the release of police videos of the shooting amid a greater security presence of National Guard troops, but the atmosphere was calmer than during previous days.