The Mexican government has condemned unauthorised building work being carried out at the ancient city of Teotihuacán, near Mexico City.
The UN’s international council on monuments and sites (Icomos) said bulldozers threatened to raze as many as seven acres at the protected site.
Teotihuacán is a Unesco World Heritage Site and is one of the most popular tourist attractions in the country.
UN officials raised the alarm about building work at the site on Monday.
Icomos Mexico said the excavation work threatened “archaeological, housing and monumental remains which are also being looted” and called on the Mexican government to decisively intervene so that experts can get in to evaluate the damage.
Experts from the site say they began to raise the alarm earlier this year after construction began, including the use of heavy machinery, on the complex’s outskirts when supervision was limited because of the pandemic.
In a statement, Mexico’s Ministry of Culture and the National Institute of Anthropology and History said it had already issued two orders to suspend construction there in March and filed a criminal complaint in April.
The ministry said it strongly condemned the building work, which it described as a threat to the nation’s heritage. It also said it was committed to defending the heritage site.
The AP news agency reports that owners of nearby plots may be trying to turn the land into some sort of amusement park attraction.
Officials warn the area is home to some 25 archaeological structures and caves with pre-Hispanic vestiges and an online petition against the building work has gathered almost 13,000 signatures.
Best known for its twin Temples of the Sun and Moon, the Teotihuacán site attracted millions of visitors a year before the pandemic hit.
The ancient city is the largest archaeological site of its type in the Americas and its ruins have long been shrouded in mystery.
Located about 50km (30 miles) northeast of Mexico City, Teotihuacán was designated a Unesco World Heritage Site in 1987.