New York officials have announced that the centrepiece tower to replace the World Trade Centre in New York will be complete in 2013.

The site has been earmarked for a vast reconstruction project to replace both towers, which were knocked down by terrorists in commercial aircraft in 2001.

The project has already been gathering pace and contributing to a boom around the surrounding area.

Only days ahead of the ninth anniversary of the September 11th attacks, city officials have said the Manhattan neighbourhood will be reborn with a new building, memorial pools and a massive plaza.

New York mayor Michael Bloomberg has said the principal tower in the new complex in now up to 36 floors out of the 106 on the blueprints.

Work is also progressing on a memorial site featuring two waterfalls, marking the fallen Twin Towers.

The memorial site, featuring the plaza, waterfalls and a stand of oak trees to commemorate those killed in the original towers, will be open in 2011.

In 2013 towers one and four will admit their first tenants.