Egypt is investigating a video which appears to show a Danish couple scaling the Great Pyramid and posing naked.
The alleged incident has sparked outrage in the conservative Muslim country.
Prosecutors will explore whether the video is real, and if so how they were able to climb the 140m (460ft) tall structure, state-run newspaper Al-Ahram reports.
Officials had initially suggested the footage might be fake.
The Great Pyramid of Giza, also known as Khufu or Cheops, is one of the seven wonders of the ancient world
A photographer said he and a friend had spent several hours “sneaking around” before making the climb.
The Egyptian antiquities minister told MPs on Sunday that prosecutors were investigating whether the Danish couple “really filmed an explicit pornographic video” at the famous site in Giza.
Khaled al-Anani, quoted by Al-Ahram, said they have been asked to determine whether the video was real or fake, and to prosecute any officials found to be negligent.
Scaling the pyramids was “strictly forbidden”, he added, calling the images a “violation of public morality”.
What does the video show?
The three-minute edited video, which was uploaded to YouTube by Danish photographer Andreas Hvid, shows a woman climbing what he says is the tallest pyramid in Giza at night.
It includes a photo of the couple, with the woman’s face blurred, posing side by side atop the 4,500-year-old pyramid.
The final shot shows the woman, her back to the camera overlooking the Cairo skyline, remove her top.
The photographer also posted an image of the couple apparently lying together naked on top of the pyramid during daylight.
What was the reaction?
The video and photo, which went viral on social media last week, has provoked widespread anger both in Egypt and abroad, with many condemning the stunt as disrespectful to Egyptian history and heritage.
Responding to Mr Hvid’s video on Facebook, one woman wrote: “Such a shame. This has been completely disrespectful behaviour to another land, another culture, another way of living… It shows little understanding of respecting another religion and culture.”
People from Denmark also weighed in with their criticism of the stunt:
But the head of Egypt’s antiquities council, Mostafa al-Waziri, has suggested the photo may have been created by image-editing software Photoshop, newspaper al-Masry al-Youm reports.
What does the photographer say?
In his YouTube post, Mr Hvid said he and his friend had entered the site of the Great Pyramid in late November.
“Fearing to be spotted by the many guards, I did not film the several hours of sneaking around at the Giza Plateau, which lead up to the climb,” he added.
He told Danish tabloid Ekstrabladet he had been dreaming of climbing the giant structure “for many years”.
“I’m sad that so many people have become so angry. But I have also received a positive response from a lot of Egyptians – something I think is worth remembering.”
Mr Hvid denied they had sex on top of the pyramid, and said they were merely posing for the photo shoot.
The photographer has posted a series of images of nude figures on high rises and in unusual locations around the world on his website.
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Has anything like this happened before?
Climbing the pyramids was banned in the 1980s after a number of tourists died attempting to scale them.
But that hasn’t stopped some rule-breakers.
In 2016, a German teenager was banned from Egypt for life after climbing the Great Pyramid to take photos and videos.
He managed to avoid a three-year jail term after authorities decided not to prosecute him.
A year later, a Turkish national was briefly detained by police for scaling the ancient Egyptian monument.
In 2015, Egyptian authorities investigated reports of footage posted online apparently showing nudity and sexual acts by a group of Russian-speaking tourists near the Giza site.
The conservative Muslim country has seen a number of high-profile Egyptians convicted in recent years of performing indecent acts in public.
Just nine days ago, actress Rania Youssef was summoned to court for wearing a revealing dress to the Cairo Film Festival.