Nazi hunter Dr. Efraim Zuroff of the Los Angeles-based Simon Wiesenthal Center said on Wednesday that the discovery of a mass grave near Odessa this week was not surprising. "Ukraine is full of mass graves and is one of the biggest Jewish graveyards in the world," he told The Jerusalem Post. Zuroff, director of the center's Israel office, added that he expected additional sites to be found in Ukraine, where hundreds of thousands of Jews were murdered. "I'm not surprised that, even in these days, there are discoveries such as these. It underscores the enormous scope of the plans of annihilation of the Nazis and their collaborators in Eastern Europe," Zuroff said. He said that it was imperative to map out and find the additional sites with the help of aging Holocaust survivors who remember the mass killings carried out by the Nazis and their Ukrainian and Romanian collaborators. Ditch-diggers discovered the mass grave, believed to contain thousands of Jews slaughtered in Ukraine during World War II, a grim finding in a nation one Holocaust expert said had been "an enormous killing field." Odessa's chief rabbi, Shlomo Baksht, wants to erect a fence around the site and erect a monument to the victims this year. The grave was found by chance last month when workers were laying gas pipelines in the village of Gvozdavka-1, about 175 kilometers northwest of the Black Sea port city of Odessa, regional Jewish community spokesman Roman Shvartsman said Tuesday. The Nazis established two ghettos during World War II near the village and brought Jews there from Odessa and what is now the nation of Moldova, Shvartsman said. In November 1941, Nazi officials set up a concentration camp in the area and killed about 5,000 inmates. "Several thousand Jews executed by the Nazis lie there," Shvartsman told The Associated Press. Shvartsman said that the Jewish community was aware of the mass murder at the time, but no one knew where the bodies were buried. Yitzhak Arad, a Holocaust scholar and former director of Yad Vashem, said the area was known to be a site of mass executions of Jews during the Holocaust. He said he found that some 28,000 Jews were brought there from surrounding towns and that 10,000 died - murdered at a rate of around 500 people a day. Anatoly Podolsky, director of the Ukrainian Center for Holocaust Studies, said there were believed to be some 250 to 350 mass grave sites dating from the Nazi occupation, during which some 1.5 million Ukrainian Jews are believed to have been killed. The number includes those massacred near their homes and those deported to death camps elsewhere. Podolsky said most of the sites were located after the 1991 Soviet collapse, but that there were still some left to find. Ilia Levitas, the head of Ukraine's Jewish Council, put the number of mass Jewish graves in the country at more than 700. According to Shvartsman, the names of 93 Jews killed at the Gvozsdavka-1 site have been established. He said Jewish community members planned to conduct studies at the newly found site to identify victims. "We must figure out their names. It is our debt to the victims and survivors," he said. Ukraine's Jewish population was devastated during the Holocaust. Babi Yar, a ravine outside the capital, Kiev, where the Nazis slaughtered some 34,000 Jews over two days in September 1941, is a powerful symbol of the tragedy. About 240,000 Jews were killed by the Nazis in the Odessa region, which was occupied by the German-allied Romanians, according to Shvartsman. He said a mass grave with remains of about 3,500 Jews was found in the region last year.