A rusted 1.5 metre-tall piece of landing gear believed to be from one of the hijacked planes destroyed in the Sept. 11 attacks has been discovered wedged between a mosque site and a luxury high-rise apartment building near the World Trade Center.

The twisted metal part includes a clearly visible Boeing identification number, New York Police Department spokesman Paul Browne said Friday. It has cables and levers on it and is about a metre wide and half a metre deep.

9/11: 10 years later

"The odds of this being wedged between there is amazing," Browne said, adding it was not surprising that it went undiscovered for more than a decade given the location. "It had to have fallen just the right way to make it into that space."

Other World Trade Center wreckage had been discovered at the buildings and around the area in years past.

The piece of equipment was discovered Wednesday by surveyors inspecting the lower Manhattan site of a planned Islamic community centre, at 51 Park Place, on behalf of the building's owner, police said.

An inspector was on the roof and noticed the debris and then called police who secured the scene, documenting it with photos.

Police detectives and National Transportation Safety Board investigators will determine whether the equipment is from the American Airlines plane or the United Airlines plane that slammed into the twin towers on Sept. 11, 2001, destroying the towers and killing nearly 3,000 people.

Islamic centre faced street protests in 2010

When plans for the Islamic centre, about three blocks from ground zero, were made public in 2010, opponents said they didn't want a mosque so close to where Islamic extremists attacked. They argued the site was "sacred" because landing gear from one of the hijacked Boeing 767 jets had punctured the roof of the building on Sept. 11.

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The piece of equipment was discovered Wednesday between two structures by surveyors inspecting the lower Manhattan site of a planned Islamic community centre. (NYPD)

During street protests, they clashed with supporters of the centre, who said it would promote harmony between Muslims and followers of other faiths.

The building includes a Muslim prayer space that has been open for three years. After protests died down, the centre hosted its first exhibit last year. The space remains under renovation.

Donna Marsh O'Connor, who lost her daughter Vanessa Lang Langer in the attacks and is a member of September 11th Families for a Peaceful Tomorrow, called the landing gear discovery "bizarre."

O'Connor is a supporter of the Islamic centre and said the fact that the plane fragment was found there "makes me think that this was the right place for a centre that was going to heal the divide."

In a statement, Sharif El-Gamal, the president of Soho Properties, which owns 51 Park Place, said workers called the city and the police as soon as they discovered the landing gear. He said the company is cooperating with the city and the police to make sure the piece of equipment "is removed with care as quickly and effectively as possible."

The medical examiner's office will complete a health and safety evaluation to determine whether to sift the soil around the buildings for possible human remains, police said.

Patricia Riley, whose sister Lorraine Riley was killed in the Sept. 11 attacks, called the landing gear discovery "very strange."

"Twelve years later we are still finding remnants of the attack on our country," she said. "... For years to come we'll continue to find things that we didn't see before. Hopefully they'll serve as a reminder that we have to stay vigilant."