A Sydney construction worker narrowly avoided death on Monday morning, when a stack of concrete sheets hit him after falling two storeys.

Witnesses said the man was standing on a truck when a stack of concrete panels being carried by a crane dislodged on a construction site about 11.30am.

A slab of concrete fell while being lifted by a crane, hitting a worker below. Credit:Ben Rushton

"It fell about 12 metres,’’ said a worker on the Ultimo Road site, who did not want to be named. ‘‘It wasn’t restrained properly."

The man worked as a ‘‘dogman’’ on the site, a job that requires guiding a crane operator as he moves a load.