Latest reports indicate the death toll in Saturday’s crane collapse in New York’s Manhattan has now risen to seven.

Two more construction workers and another female were killed when the 19 storey high crane broke away from an apartment block under construction.

Sniffer dogs and heat-sensing cameras have been brought in a bid to find survivors of the worst accidents of its kind in recent years, which killed six construction workers and injured at least 17.

It also wrecked a four-storey townhouse and hit parts of five other nearby buildings.

The accident reportedly occured after workers tried to extend the crane to start on a new level of the building.

Investigations are now said to be examining whether human or mechanical error was the cause of the incident.

American crane expert and general manager of the Crane Inspection and Certification Bureau, John Cole, said inadequate training was responsible for most crane accidents.

He said: "A lot of people here look at training not as an investment but as a cost. Usually accidents happen when manufacturer's instructions are not followed and a lot depends on whether the people involved have proper training."

However, New York City officials have stated the crane had passed a routine inspection on Friday last.

Source: Contract Journal