Ice daggers threaten New York pedestrians as big chill begins to thaw

Residents of US cities facing one of the most brutal winters on record have been dealing with something far more dangerous than snow: ice falling from skyscrapers.

Several streets around New York's 1 World Trade Centre, the nation's tallest building, were closed on Wednesday morning when wind-blown shards of dagger-shaped ice hit the pavement near the 541-metre building.

The streets reopened by mid-afternoon.

Around the nation, pavements around high-rises in cities have been cordoned off because of falling icicles and rock-hard chunks of frozen snow. Experts warn it could get worse over the next few days as a thaw sets in over much of the United States.

"The snow starts to melt and the liquid drips off and makes bigger and bigger icicles, or chunks of ice that break off skyscrapers," said Joey Picca, a meteorologist at the National Weather Service in New York. The city has had 123cm of snow already this year.