NEW YORK -

Prince Harry bowed his head in prayer at Ground Zero on Friday, then toured the Sept. 11 attack site and shook New Yorkers' hands in his first official visit to the United States.

"Big question -- when is this supposed to be finished?" the 24-year-old prince asked two officials showing him rebuilding plans of the World Trade Center site.

The prince laid a wreath of peonies, yellow and white roses at a spot on the site overlooking the Sept. 11 memorial under construction, then bowed his head for several minutes.

Attached to the wreath was his handwritten note, reading "In respectful memory of those who lost their lives on Sept. 11, 2001, and in admiration of the courage shown by the people of this great city on that day." It was signed, "Harry."

Harry spoke for about 15 minutes with relatives of four Sept. 11 victims in his first New York City stop. He was to visit a garden memorializing Sept. 11 victims and a veterans centre in Manhattan later Friday.

"It's a very kind gesture on his part," said Chip Callori, whose brother, Joseph Amatuccio, was killed at the trade centre on Sept. 11, 2001. "For him to realize that this is a sad but important part of our history."

The prince then visited a firehouse across from Ground Zero, while hundreds of New Yorkers strained for a glimpse of him behind police barricades. He broke away from his security detail to a street around the corner to look at a bronze memorial to 343 firefighters killed at Ground Zero.

He then chatted with some tourists and shook several hands before going to his next stop.

Gov. David Paterson and Christopher Ward, executive director of the agency that owns the trade centre site, attended the prince's visit.

"It's a very special visit," Ward said. "Obviously, the history of the United States and our partnership in fighting wars around the world makes it even more special."

The prince was to formally name the British Garden in downtown's Hanover Square to honour the 67 British victims of the terrorist attack, then visit the Veterans Affairs Medical Center in Manhattan to tour the prosthetics facilities and a clinic that treats people with post-traumatic stress disorder.

A British soldier who lost both legs in an explosion in Afghanistan was to attend the ceremony in New York.

Harry, the younger son of Prince Charles and the late Diana, Princess of Wales, is third in line to the British throne.