Robert McTackett, 53, was crushed under an L-shaped concrete container at the Brick & Block manufacturing plant on Foreshore Rd.

The concrete block fell from a fork-lift as it was reversing across an area near the plant entrance about 11am yesterday.

Mr McTackett had been using a shovel to clear material from the base of the concrete block and was standing directly in its path when it fell.

"(The driver) was in the process of lifting it and moving it and when reversing it appears it's toppled off and crushed him," said ambulance district officer Norman Rees.

"It trapped him from the shoulders down."

Mr McTackett was pinned against a retaining wall under the slab for 20 minutes before he was freed by police and ambulance rescue workers.

Ambulance rescue helicopter Rescue 26 was flying overhead en route to Sydney when the accident occurred and was able to land on a wharf near the site not long after Mr McTackett became trapped.

"(Helicopter) paramedics and a doctor were there within minutes and then assisted the road crew paramedics with treatment," Mr Rees. "He had the best possible care, even though the outcome wasn't what we wanted."

Police and ambulance rescue workers stabilised the cement block using air bags and blocks before taking the weight off Mr McTackett, who was unconscious.

He was taken by ambulance to Wollongong Hospital in a critical condition and later died from his injuries. Mr Rees said the fork-lift driver had refused medical treatment.

Brick & Block manufactures building blocks from steel industry waste for use in commercial and residential buildings and has been operating from Port Kembla since 2005.

WorkCover NSW sent investigators to the site yesterday afternoon and promised a full and thorough investigation into the fatality. Brick & Block declined to comment.