Explosions triggered by molten aircraft metal reacting with water from sprinkler systems may have felled the Twin Towers after the 9/11 attacks, according to a new theory.

A staircase at the World Trade Centre that proved a lifeline for countless September 11 escapers and survived the devastation will be moved from the site his weekend.

In New York, more remains of the victims from September 11th terror attacks have been discovered.

The sale of World Trade Centre memorabilia on the internet, including recordings of emergency service transmissions, is sparking outrage.