Image copyright AP Image caption The former mayor said Donald Trump is stretching the truth

The former mayor of New York City has said there were "pockets" of people celebrating when the World Trade Center towers fell on 11 September 2001.

But Rudy Giuliani, who was mayor at the time, disputed claims by Republican presidential candidate Donald Trump that thousands of people were involved.

Mr Trump's comments have been refuted by local political leaders because of a lack of evidence.

New Jersey Governor Chris Christie simply said "it didn't happen".

Mr Giuliani, who ran unsuccessfully for the 2008 Republican nomination himself, said: "We did have some [reports of] celebrations, there were pockets of celebration, some in Queens, some in Brooklyn."

He said in one specific report which was later proved to be true, owners of a sweet shop were celebrating and children from a nearby housing development "beat them up".

But he said Mr Trump was wilfully exaggerating the numbers and he himself "would've been thrown out of the race" had he made such an inflated claim during his 2008 campaign.

Former New York City Police Commissioner Bernard Kerik later backed up Mr Giuliani's comments, saying "10-50" people were reported to be celebrating in different areas throughout the city.

Image copyright Getty Images Image caption Mr Giuliani said small groups of people celebrated

Businessman Mr Trump, who comes from New York and runs his billionaire property empire from the city, has come under constant attack for days, ever since he made his controversial 9/11 remarks at a rally in Alabama.

The mayor of Jersey City, which Mr Trump named, said no such thing happened and accused the Republican of "shameful politicising".

And New Jersey Governor Chris Christie, his Republican rival in the race for the White House, said it was not true.

"It didn't happen and the fact is, people can say anything, but the facts are the facts, and that didn't happen in New Jersey that day and hasn't happened since."

Mr Trump leads the Republican race to be presidential nominee, two months before voting begins in the primary contests.

He has also urged increased surveillance of Muslims in the US, in light of the Paris terror attacks that killed 130 people.