THE WHITE HOUSE was put on temporary lockdown last night after a smoke bomb was thrown over the gates.

Hundreds of Occupy protesters had gathered outside the the gates after marching on the US Capitol and supreme court in what the Washington Post reports had been planned as the movement’s first national gathering since it began in New York in September.

Police dispersed the crowds after the smoke bomb was thrown into the property’s grounds, but no arrests were made, according to the AP.

President Obama and wife Michelle Obama are not believed to have been in the White House at the time of the incident – they were celebrating the first lady’s 48th birthday at a steak restaurant in the city last night.

According to the New York Times, a Secret Service spokesman said that the exact nature of the device thrown over the fence was being investigated.

Despite moves by authorities in other cities to push the protests out of city parks, Occupy protesters have been permitted to use two public squares near the White House by the US National Park Service.

(Video via AssociatedPress)