Ulan Bator, Mongolia ? An American-financed expedition to find the tomb of legendary conqueror Genghis Khan has stopped work after being accused by a prominent Mongolian politician of desecrating traditional rulers’ graves.

Genghis Khan overran much of Asia before his death in 1227, gaining a reputation as a mass murderer. But at home he is the hero of Mongolia a reminder of an era before this sparsely populated land was dominated by its giant Chinese and Soviet neighbors. He appears on the currency and his portrait hangs in the entry hall of the Foreign Ministry.

Yet Genghis Khan’s grave site is one of archaeology’s enduring mysteries. According to legend, in order to keep it secret, his huge burial party killed anyone who saw them en route to it; then servants and soldiers who attended the funeral were massacred.

The latest search financed by private investors and led by a University of Chicago professor announced last summer that it found a possible tomb site. But work stopped this summer after former Prime Minister Dashiin Byambasuren wrote to President Natsagiin Bagabandi, accusing the team of driving cars over sacred soil and erecting buildings near a historic wall. Byambasuren said they had defiled the remains of the dead.

The letter asked the president to investigate and called for expelling the team from the site. He expressed disappointment that the 3-year-old Genghis Khan Geo-Historical Expedition had commercial interests associated with the excavation.

The site, called Oglogchiin Kherem, is 200 miles northeast of the Mongolian capital of Ulan Bator in Hentii province, the homeland of Genghis Khan.

Digging this summer revealed a series of flagstones that covered 11-foot-long trenches. Horse teeth, animal bones and a human skull were found amid the rocks, though no grave has been sighted.

“We hope we can go back next year, but for now the future of the expedition is unknown,” said historian John Woods, the expedition’s leader.

Expedition founder Maury Kravitz has been trying to find the grave for 40 years and organized investors who provided $1.2 million.

The Mongolian government, which has already issued permits to excavate the site, has not responded to Byambasuren’s letter.

Woods said he had tried to reassure Byambasuren about the expedition, noting that a majority of its members are Mongolian and that it had followed Mongolian law.

The National Security Council demanded to know what commercial interests were at stake, and Kravitz said a documentary was being prepared, along with a movie about Genghis Khan’s life. Woods said investors don’t expect to profit from the site itself, but will raise money abroad from the movie and documentary.