We in the scrap trade do not attach any importance to the source of our consignments

Madras scrap dealer

Salvaged iron rods will also be used in reinforced concrete structures.

The debris from the collapsed Twin Towers was bought at auction by New Jersey scrap processor Metal Management from the New York City authorities.

Some was then sold to a Dubai dealer and 33,000 tonnes of it was sold again to a scrap dealer in the south Indian city of Madras for $120 per tonne.

The consignment has arrived in India on the bulk carrier Borzna and is being unloaded, ready for processing.

Collapsed bridges

The dealer involved, who declined to be named, says wreckage from old bridges and buildings is a common source of material for recycling in India - along with the more usual old cars and old ships.

"We in the scrap trade do not attach any importance to the source of our consignments," he said.

"Many times they come from broken mansions, collapsed bridges and disasters all over the world."

Three other ships carrying similar amounts of World Trade Center wreckage are headed for China, and one ship is on its way to the port of Kandla in the western Indian state of Gujarat.