Demonstrators have forced the closure a shopping mall near Ferguson in the US state of Missouri, at the start of the holiday shopping season as protests over the killing of an unarmed black teen by a white police officer target some retailers around the country.

After a quiet Thanksgiving Day, protesters were out in force on Friday to vent their anger at Monday's decision by a grand jury not to indict Officer Darren Wilson in the August 9 shooting death of 18-year-old Michael Brown in the St Louis suburb.

Activists around the country said they were encouraging a boycott of Black Friday sales to highlight the purchasing power of African Americans, and to draw links between economic and racial inequality.

The killing of Brown, which has renewed a debate over race relations in the US and the treatment of blacks and other minorities by police, has prompted months of sometimes violent protests in Ferguson and sympathy protests elsewhere.

At the upmarket Galleria near St Louis, demonstrators chanted "No Black Friday" before singing carols and then briefly lying on the floor, leading officials to close the mall.

National Guard troops were posted outside, and mall security stopped anyone from entering, telling disappointed bargain hunters the shopping centre was shut for the rest of the day.

Ferguson marches

Ferguson itself was peaceful after more than 100 arrests on Monday and Tuesday, when some demonstrators reacted to the grand jury's decision by looting or burning businesses, and officers in riot gear fired tear gas and smoke bombs to disperse crowds.

About 100 protesters marched up and down the road outside the Ferguson police department late on Friday.

As National Guard troops in camouflage and combat helmets looked on, the crowd chanted: "Soldiers, turn your guns around! Shoot this racist system down!"

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One Walmart store near Ferguson decided to cancel Black Friday sales, and merchandise was moved to other locations in the St Louis area, employees said.

More than 200 people in New York City sought to disrupt shopping on Friday with a protest in front of the Macy's flagship store in Herald Square and marched into the ground floor as staff and shoppers looked on in apparent surprise.

Demonstrators later marched through the streets of New York, and a police spokesman said officers arrested seven protesters for disorderly conduct.

Similar protests were staged in other cities, including Chicago, Seattle and San Francisco and Oakland in California, on Black Friday, when many retailers offer deep discounts and shoppers traditionally turn out in droves.

Hundreds of protesters marched through San Francisco's commercial centre on Friday night packed with shoppers, the Associated Press news agency said.

KGO-TV said some in the crowd used hammers to smash the windows of stores in the touristy Union Square. The TV station said crowds marched through the heart of the shopping district and arrived at the popular Union Square, where police stopped them from disrupting the lighting of a Christmas tree.

In Oakland, about 16 people were arrested after chaining themselves to a train during a demonstration at a Bay Area Rapid Transit (BART) rail station, a BART spokeswoman said.

In Los Angeles, where more than 300 people have been arrested in Ferguson-related demonstrations this week, about 120 protesters marched through the streets.

Source: Agencies