BERLIN • Experts have raised questions about assertions by two German artists that they used a concealed mobile device to scan the bust of Queen Nefertiti at the Neues Museum in Berlin and then released the resulting data online in a project meant to question museum policies and notions of cultural ownership.

The artists, Nora al-Badri and Jan Nikolai Nelles, said they scanned the 3,000-year-old bust during a visit to the museum in October, using a modified version of a Kinect, a consumer-grade motion sensor.

In December, they released online what they said was the resulting data, allowing anyone to make a copy of the bust with a 3D printer. They also released a video that they said showed them scanning the bust at the museum and made two of their own copies, which they delivered to Egypt.

The project, called The Other Nefertiti, attracted wide attention, with many praising the artists' message of openness, their guerilla tactics and their clever use of scanning technology.

But as the story spread, some 3D scanning experts began asserting that the data the artists released was of too high a quality to have come from a Kinect, which was developed by Microsoft for Xbox 360. They suggested that the artists had somehow acquired the museum's own scan of the bust, scanned a high-quality copy or produced the scan by some other means.

Mr Fred Kahl, a designer and 3D scanning expert who developed a 3D portrait studio for which he says he has made more than 10,000 scans using a Kinect, said: "The scan shows far more definition than is ever remotely possible" with the device the artists say they used.

"You look at the texture of the surface of the model they released and it has very fine, level detail of the cracks around the base and the texture on the headdress," he said, adding that the scan that Badri and Nelles released contained more than 2 million mesh units, known as polygons, whereas he has "never captured a Kinect scan with more than 600,000".

In a blog post, Mr Kahl pointed out that the Kinect would have required an uninterrupted line of sight to the statue during scanning, but the video shows Badri uncovering the device only intermittently. He and others said the protective glass encasing the bust would have been a further impediment.

Badri and Nelles said in a recent interview that the data they had released was collected during their October museum visit and assembled by outside experts - hackers who declined to be identified.

While the artists maintained last Thursday that the scanning of the bust had taken place as they had initially described, they said they could not confirm that the data they released in December was the result of that scan, nor would they identify their anonymous partners or produce raw data proving that a scan indeed occurred.

When asked whether they believed when they released the data that it had been derived from their own scan, Badri said cryptically that they "didn't really think that way", adding that this was "for legal reasons".

She and Nelles also stressed that they "are not technicians" and had been unfamiliar with how to use the scanner, which they said the hackers gave them. The artists denied any knowledge of the data having been acquired through theft or a leak within the museum.

"We came to them and asked how to do it," Nelles said, referring to the hackers. "They came up with the set-up, the device."

The hackers, he added, provided them with a USB stick containing the Nefertiti scan "and I made it a torrent and then I put it online".

Badri said: "We didn't talk about the quality of the scan. In the conversation, they told us just not to ask questions."

Barry Threw, a media artist who also runs #NewPalmyra, an online platform devoted to creating 3D copies of ancient artefacts, said he believed it was "extremely probable that the scan data was acquired by some other means".

The Neues Museum has made its own high-quality scans of the bust of Nefertiti, which it has not released to the public.

NEW YORK TIMES