Ferguson shooting protesters lay on a shopping boycott for Black Friday

Demonstrators shut down a shopping mall near Ferguson, Missouri, at the start of the holiday shopping season as protests over the killing of an unarmed black teen by a white police officer turned on some retailers around the United States.

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

Activists across the country said they were encouraging a boycott of Black Friday sales to highlight the purchasing power of black Americans, and to draw links between economic and racial inequality. "You have to disrupt business as usual for this to happen and that's the only thing that's ever made change," said Sergio Uzurin outside Macy's flagship store in New York.

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

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

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