JERUSALEM — When it uprooted trees recently to expand a road near the fence of the Jewish cemetery in the Brodno district, the Warsaw municipality unearthed bones.

"Nobody knew when they were building the road that the land was a graveyard, because the cemetery already was fenced in the early 1980s," said one Polish Jewish community official. "No one questioned what was outside the fence."

Taking a lesson from the experience in Prague, where the discovery of a medieval Jewish cemetery at a commercial construction site caused an international commotion, Warsaw officials immediately halted construction and are working with European rabbis to demarcate the burial ground and preserve the site's sanctity.

There are between 5,000 and 10,000 Jewish cemeteries and mass-burial sites in Europe, and those are only the ones that have been identified or presumed to exist, according to Samuel Gruber, the director of the Jewish Heritage Research Center.

"There are probably countless cemeteries that have been obliterated and can't be identified at all, many of which were obliterated centuries ago," Gruber said in a recent interview from his office in upstate New York.

Cemeteries are often seen as valuable pieces of real estate that are ripe for development as Eastern Europe makes the transition to a market economy and privatizes land ownership to encourage development.

"One of the downsides of democratization and the new economies is that in some places there is almost a Wild West type of real estate speculation, and unless cemeteries are specifically protected, they are prime sites for development," Gruber said.

The recent discovery of cemeteries in Brodno and Prague, and earlier discoveries in York, England, and Hamburg, Germany, are merely harbingers of things to come, experts say.

"In the next 100 years it is going to happen 1,000 times, because Eastern Europe is a graveyard…Poland alone has well over 1,000 Jewish cemeteries," said Michael Lewan, chairman of the U.S. Commission for the Preservation of American Heritage Abroad.

"It is inevitable that some day, some guy building his version of McDonald's is going to do it on a graveyard, not because he is a bad guy, but because that is the land he bought," he said. "The forces of economic growth clash with the forces of historical preservation and the Talmud."

The problem of neglected, abandoned, and obliterated graveyards exists throughout Europe, according to Gruber, who surveys cemeteries for the American commission. Cemeteries have fallen into disuse because of the Holocaust, which left areas depopulated, communities destroyed and led to emigration. All cemeteries have what experts call some kind of encroachment problem, in which the site has been violated by inappropriate development, such as buildings, playgrounds, parks and even agriculture. Vegetation is rampant, as is vandalism.

"Vandals, since the war years, have pillaged cemeteries not because of anti-Semitism but because cemeteries are quarries for building stones," Gruber said, adding that specifically anti-Semitic desecration is "very rare."

The American commission is a quasi-official agency that encourages the preservation and protection of buildings, monuments, and cemeteries connected with the heritage of Americans from the 22 countries in Central and Eastern Europe and the former Soviet Union. It has dispatched its commissioners, with the support of the U.S. State Department, to meet with European prime ministers and cultural officials to win commitments to save heritage sites.

Any official European governmental commitment to protect graveyards is only one of numerous factors that must be orchestrated to preserve Jewish cemeteries in Europe.

There must be a legal obligation to protect the sites, the political will to compel compliance, financing for the sites and those displaced by the discovery of graveyards, and cooperative relations between local Jewish communities and Jews abroad.

That position was accepted by the Ukrainian federal government in 1998 when it issued an executive decree forbidding construction on all cemeteries and preventing their privatization — after two years of prodding by the U.S. commission and Agudath Israel World Organization. This was a "historic development," said Harry Reicher, the organization's international affairs director in New York. However, he noted that it was essentially a stopgap measure in the absence of national legislation protecting the sites.

A different sort of problem has arisen in the eastern part of Germany, where the former communist regime did not respect cemeteries, and issued permits for building on the sites. The German federal government professes sympathy, but says it is powerless, because reunified Germany is a decentralized nation where the power is vested in the länder, or states.

"What the German government has said through its Interior Ministry is, 'We learned the lessons of the Nazi tyranny and have divided power,'" Reicher said. "But one of the ironies is that they are citing that in response to requests by the worst victims of that very tyranny for respect for their cemeteries, for their dead, and in many cases that means people who were killed by the perpetrators of that very tyranny."

However, the most wrenching problem in the protection of cemeteries stems from the battles between the European Jewish communities and the Jews abroad over how high a priority cemeteries should be.

"All of Europe is an area where shrunken or nonexistent Jewish communities have existed or do exist. And the Jewish communities in Prague, in Lvov, in Kiev, in Bratislava…their primary concern is to preserve the small Jewish community that is there, to take care of the elderly and have schools for the kids," Stolberg said. "There is a difference in focus between international Orthodoxy and all the local communities in Europe," he added.