ISTANBUL - A group of lawyers, scientists and bureaucrats met last week on the banks of the Tigris outside Hasankeyf, a town in southeastern Anatolia that goes back several millenniums and is slated for submersion by a dam under construction downriver.

The meeting was the official start of an investigation, ordered by a Turkish regional court, to assess the cultural value of Hasankeyf and the damage that the Ilisu dam project would inflict on it.

Raising his voice above the yapping of local dogs, Judge Mustafa Arik swore in three scientists - a hydraulic engineer and two archaeologists - appointed by his administrative court in neighboring Diyarbakir, television footage of the event by the Dogan news agency shows. The court has the power to halt construction of the dam. The fate of Hasankeyf and of one of Turkey's biggest and most controversial hydro-power projects now hangs on the experts' report, due within three months.

The inquiry may signal the end of decades of battling over the project, which the government says will bring jobs and wealth to an impoverished region, but which opponents say is environmentally and culturally destructive.

European lenders pulled out of the €1.1 billion, or $1.5 billion, project in July 2009, citing concerns about environmental impact, resettlement policies and the destruction of cultural treasures. But Ankara rallied quickly, raising domestic financing to fill the gap, resuming construction on the dam last year and even beginning to resettle the population in the catchment area.

The project is now moving ahead at high speed. Prime Minister Recep Tayyip Erdogan has asked the building consortium to complete the dam by mid-2014, two years ahead of target. But the case before the court in Diyarbakir could yet throw a wrench in the works.

As the surveyors struck out for a first ramble around Hasankeyf last week, they were trailed by the litigants - a dozen government lawyers and officials charged with defending the dam project and the sole plaintiff, Murat Cano.

For Mr. Cano, a lawyer from Istanbul, this inquiry has been a long time coming, as he recounted during an interview in his office last week. He filed his complaint in January 2000, arguing that Hasankeyf was protected by Turkish laws for the preservation of historical and cultural sites, as well as by the European Convention on the Protection of the Archaeological Heritage.

"In Hasankeyf, we have Byzantium, we have Rome, we have the Assyrians, the Arabs, the Seljuks, the Sassanids, the Ottomans - there are relics of all the civilizations that have existed here in upper Mesopotamia," Mr. Cano said. "This cultural heritage does not belong to you or to me, it belongs to all of us in the world. We are guardians, custodians only."

The case was shunted around the courts in jurisdiction disputes and other legal wrangling for more than a decade, until the Diyarbakir court appointed the experts last month.

While delighted that the survey is now under way, Mr. Cano fears that time is running out. The Culture Ministry, in charge of relocating monuments from the catchment area and preserving others underwater, "has absolutely no viable plans" to do so, Mr. Cano said in a second interview this week, after touring Hasankeyf and the Ilisu construction site with ministry representatives. "Meanwhile, construction on the dam is going full steam ahead. They are trying to create a fait accompli."

The dam had been scheduled for completion in 2016, until Mr. Erdogan intervened to speed things up.

"That seems like a very long time to me," Mr. Erdogan said in October at the inauguration of a new village for the inhabitants of Ilisu, which is among the 200 settlements that will be inundated. "Let's have it completed within the first half of the year 2014 at the latest."

The General Directorate of State Hydraulic Works, the government agency in charge of the project, confirmed Tuesday that it was working to meet this target. Work on the main body of the dam is to commence next month, it said in an e-mailed statement.

Conservation work in Hasankeyf, by contrast, is proceeding far more slowly, as Culture Minister Ertugrul Gunay has conceded. "In my opinion it will take quite some more time," Mr. Gunay said during an interview last month.

The minister said he had been pressing his cabinet colleagues to find a "technical solution." "In the case of a unique historical town like Hasankeyf, I think we should proceed much more carefully and patiently," he said.