www.guardian.co.uk To the naked eye, they look like mounds of soil on a plain of flat farmland. But to archaeologists, the network of small hills represents a treasure trove of ancient Persian culture now endangered by organised plunder and intensive agriculture.

Iranian cultural heritage officials are on a collision course with rural communities after embarking on a legal crusade to reclaim the hills and nearby land on which, they believe, once stood the city of Jondishapour, where the Persian King Shapour I vanquished the Roman emperor Valerian more than 1,700 years ago.

They have issued cultivation bans and pressed criminal charges against dozens of farmers accused of destroying parts of the archaeologically sensitive 300-hectare (741-acre) site. At least one farmer has been jailed and many others face imprisonment. The cultural heritage department plans to issue compulsory purchase orders buying the tenant farmers' leases, effectively expelling them from government-owned land which their families have cultivated since the rule of the last shah, Mohammed Reza Pahlavi.

In response, some farmers are threatening to seize neighbouring land by force.

The row has been prompted by plans for excavations as the first stage in a project aimed at resurrecting Jondishapour as a symbol of national achievement - part of a broad effort to revive Iran's age-old Persian heritage neglected in the aftermath of the 1979 Islamic revolution.

Situated in Khuzestan province, southern Iran,Jondishapour became the capital of the Sassanian dynasty after it was built by 70,000 Greek soldiers captured in the Roman defeat. Its university was renowned for science, astronomy and philosophy, while its medical centre has been credited with establishing the modern hospital system.

Farmers stand accused of threatening that legacy by digging in the hills for relics. Discovered artefacts are sold to organised bands who, officials say, peddle them abroad at huge profit. The farmers deny the charges, insisting their only income is vegetables grown for local markets.

"To us the city of Jondishapour is of no value," said Mahmoud Shahabadi, 35, a farmer from Shahabad, who is among those facing criminal charges. "I think the whole project is just a lie to weaken the farmers and enable the authorities to do whatever they like with our land. But even if the claims are true, do you think it is worth depriving the 10,000 people of our town of their means to a living just so the cultural heritage department can see if there's an ancient city under here?"

Abdolreza Khojaste, 27, who cultivates a strip of land with his five brothers, said: "If these lands are taken away by the government, there are neighbouring areas that we are going to take, if necessary by force. Cultivating this land is our life and our sole means of earning a living." That claim is challenged by cultural heritage officials, who say many farmers search for treasures late at night using metal detectors and earth-moving equipment. Advertisements for metal detectors are common in nearby towns and villages.

Many hills are riddled with holes, and broken pottery and ancient stonework lie strewn around. At least 12 hills have been destroyed by farming and plundering since the revolution. According to local lore, some farmers have grown rich by making multiple copies of ancient coins, selling them as originals.

"The picture of poor farmers struggling to make ends meet just isn't credible to us," said Saeed Mohammadpour, legal representative for the Khuzestan cultural heritage department. "We are 100% sure they have been selling the items they have found. They want to stay on this land under the excuse of farming because digging [is] an extra source of income. They earn much more from that than farming. They are ruining the history not just of a nation but of human civilisation. They think filling their stomachs is more important than the blood of their ancestors."

The department has written to Iran's president, Mahmoud Ahmadinejad, seeking his backing.

Officials want to broaden their focus to other parts of archaeologically-rich Khuzestan where looting is rife and irresponsible farming and development widespread. The province has some of the world's oldest signs of civilisation, thought to date to 7000 BC. However, Iran's Islamic rulers may be reluctant to risk provoking unrest in a province sensitive because of its oil wealth and Arab-speaking majority, many of whom harbour separatist sentiments.