Meanwhile, Port Authority police have launched an investigation, and dispatched officers with cameras to the men’s washrooms to take pictures of the heinous scrawls.

They will hit the ladies’ rooms in the still-under-construction building on Tuesday.

PA spokeswoman Lisa MacSpadden said that such slurs are offensive and have no place at the World Trade Center or elsewhere, adding that ‘the Port Authority has zero tolerance for those who demonstrate intolerance’.

According to the New York Daily News, Tishman Construction has even vowed to fire any construction worker caught vandalizing the building with graffiti.

In a statement, the company said that “they have instructed all of the foremen and subcontractors on the job to meet with crews and reiterate this policy immediately”.

Last week the News had reported that offensive graffiti were drawn in side a building, which sparked a storm of criticism from some of New York’s elected officials and the story drew words of praise from City Controller John Liu.

Gary LaBarbera, president of the Building and Construction Trades Council of Greater New York, also said the hateful scrawls were ‘not representative of the overwhelming majority of workers who have dedicated themselves to the reconstruction of the World Trade Center’.

Tishman Construction is the company rebuilding the One World Trade Center.

John Whikehart, a white laborer from Staten Island who has worked on the tower for three years, said the people who scrawl graffiti “are idiots.”

The report found that Blacks were not the only targets of the scrawls, there were also anti-Semitic and sexist screeds, and knocks on the Irish.