Image copyright Reuters Image caption Tributes were left on the spot where Mr Garner died

A medical examiner has ruled that a white police officer's "chokehold" caused the death of a black New Yorker.

Spokeswoman Julie Bolcer said Eric Garner's death last month, which caused an outcry, had been ruled a homicide.

Mr Garner was arrested for selling untaxed, loose cigarettes and during his struggle with police officers he is heard saying he could not breathe.

The incident was filmed and in the video, one officer appeared to have his arm around Mr Garner's neck.

Ms Bolcer said his death was caused by "the compression of his chest and prone positioning during physical restraint by police", but there were other factors too, such as asthma and heart disease.

Relations between the city's minorities and the police have been under strain in recent years due to controversial use of stop-and-search.

New York Mayor Bill de Blasio said: "On behalf of all New Yorkers, I extend my deepest sympathies to the family of Eric Garner, on this day we have received the medical examiner's findings concerning the cause of his death.

"My administration will continue to work with all involved authorities, including the Richmond County district attorney, to ensure a fair and justified outcome."

Image copyright AP Image caption Mr Garner's widow broke down during a rally

The New York Police Department (NYPD) has not yet responded to the medical examiner's ruling.

Chokeholds are not allowed by the NYPD and Police Commissioner William Bratton has ordered an internal review of training.

The officer who put Garner in the chokehold has been stripped of his gun and badge while the investigation goes on, and another officer has been placed on desk duty.

Two paramedics and two other medics have been suspended without pay.

The case is also being investigated by local prosecutors.