The Libyan capital of Tripoli lies more than 1,700 miles from the ancient Iraqi city of Nimrud. But for Mustafa Turjman, head of archaeological research at the University of Tripoli, the reported destruction of Nimrud’s ruins last week by the bulldozers of Islamic State (Isis) must have seemed rather closer to home.

For Libya, like Iraq, is home to a prized array of temples, tombs, mosques and churches, including five Unesco world heritage sites. And Libya, like Iraq, is racked by a complex civil war in which Isis plays a key role.

“Everything is unpredictable,” Turjman told the Observer. “But our heritage is in danger and it’s very difficult to protect it. We [academics] can protect it through restoration, but to protect it from people and explosions is very difficult. Sites, in particular in the centre and populated areas, are very endangered and very much at risk.”

Long the crossroads between the Sahara and the Mediterranean, Libya consequently houses a unique range of treasures, drawing widely from Christian and Islamic history, the Greek and Roman eras, as well as the desert dynasties that overlapped them.

By the Mediterranean sprawls what remains of the town of Leptis Magna, one of the world’s most impressive relics of Roman history. Up the coast to the west is Sabratha, another Roman site famed for its vast amphitheatre. And along the shoreline to the far east sits Cyrene, one of the oldest colonies of the ancient Greek empire. Further south is Ghadames, one of the most ancient settlements in north Africa, which Unesco calls “the pearl of the desert”. And in the deepest south, the Acacus mountains host generations of prehistoric rock paintings, some dating back to 12,000 BC – “an open-air museum,” said Turjman, “that summarises the history of thousands of years”.

Isis affiliates in Libya have not yet targeted any of these sites, but the group dominates two towns on the Mediterranean shoreline – Derna and Sirte – and has a presence in others. So there are fears for the museums and non-Islamic sites within its reach, and for Islamic ones that do not conform to extremist interpretations of the religion. Museum entrances have been welded shut, and some smaller treasures hidden, mirroring salvage efforts by Malian academics in 2012 when extremists took over Timbuktu.

Dating back to 1000BC, Leptis Magna has some of the most spectacular Roman ruins in the region. In 2005 German archaeologists found mosaics from the first and second centuries, one of which was described as ‘a masterpiece comparable with the Alexander mosaic in Pompeii’. Photograph: Jason Hawkes

“Looking at the way Isis works, the great worry is that some people might copy them in Libya,” said Hafed Walda, soon to become Libya’s deputy ambassador to Unesco. “With this lack of security and chaos, anything could happen.”

Officials do not want to name publicly the archaeological sites they believe to be most at risk, in case they give ideas to Isis’s attention-seeking extremists. “They want the whole world to take notice, so it would be better for the media to keep it on a lower profile,” argued Ahmad Mostafa, a member of the archaeology faculty at the university of Benghazi. But behind the scenes Libyan experts nevertheless privately appealed for overseas colleagues to help avoid a repeat of what happened in Nimrud, and in a museum in Iraq’s Mosul where militants smashed ancient statues.

“Following release of the Mosul video showing wanton destruction of antiquities, there has been a lot of email traffic between Libyans working in archaeology and Arab-world representatives on the major international heritage bodies,” said David Mattingly, a professor at the University of Leicester, who has spent years excavating Roman ruins in Libya. “The message is: ‘Help. What could happen in Libya is terrible’.”

The depressing plight of Libya’s antiquities over the last few yearshints at what may be to come. During and after the fall of former dictator Muammar Gaddafi in 2011, some Libyans tried to guard monuments and ruins in their area. There were even hopes that Gaddafi’s departure would herald a new dawn in archaeological exploration. But others used the absence of law and order to loot, vandalise or build on previously protected sites. Vandalism of the Acacus rock paintings increased. Armed looters stole tiles and marbles from Tripoli’s fabled Karamanli mosque, built in 1738. And Islamist extremists desecrated shrines built by Sufi Muslims and the graves of British soldiers.

But for all the fears caused by Isis and their ilk, the most immediate threat may simply be low-level, apolitical construction. “This is the most dangerous thing facing heritage in Libya at the moment: urban encroachment and land grab,” said Walda. “People want to build on land in archaeological areas, and in many cases they destroy the archaeological heritage. There’s no law and order, and in this situation people take the law into their own hands.”

The issue is not limited to Libya: in relatively calm Egypt in 2013, villagers built an unsanctioned cemetery in the shadow of some lesser-known pyramids, amid hundreds of other violations across the country. But in Libya the problem is particularly stark. In the most egregious example, one family destroyed an entire ancient settlement near Cyrene to make room for new housing.

“It’s an example of the kind of damage and destruction that can happen in these conditions,” said Mattingly, who stressed that other Libyans were nevertheless taking the lead in trying to protect their heritage. “A landowner who’s obviously been champing at the bit to do this for a while has taken advantage of the situation and simply bulldozed the site.”

There is little that can immediately be done. In Britain, Mattingly has co-founded Endangered Archaeology, a £1.2m initiative that sees academics pore over satellite imagery to document damage to more than 1.5 million archaeological sites across not just Libya, but the Middle East in its entirety. In recent weeks his colleagues using this method discovered that Islamic tombs from the 10th century had been destroyed in the desert town of Zuwila.

The remains of the ancient Parthian city of Hatra, a 2,000-year-old site in northern Iraq which officials in Baghdad reports is being demolished by Islamic State. Photograph: National Geographic/Alamy

But yesterday Baghdad officials said Isis has begun demolishing the ancient site of Hatra in northern Iraq. In Libya, concerned officials currently have little means to prevent such damage. Armed militias control much of the country, rather than state employees. And those employees now technically work for two rival governments – a secular-leaning administration in the east, which won the most recent elections, and an Islamist alliance in the west, which ignored the results. The resulting division has hindered civil servants’ ability to coordinate the protection of antiquities.

“Libya is in a civil war, so archaeological and cultural heritage is not the top priority: there are many other issues including hospitals and schools,” said Savino di Lernia, head of the Archaeological Mission in the Sahara, a programme run by the Sapienza University in Rome. “But as a result we cannot really understand how big and widespread the damage to sites is. We don’t have the scale of destruction in Syria and Iraq, but it is possible that something on that scale could happen in Libya.”