Q. Re- question 1107. Is there an actual prohibition to be buried in a non-Jewish cemetery?

A. Talmud (Sanhedrin 46b) debates whether there is only an allusion (remez) in the Torah for the need of burial from the posuk (Devorim 21: 23), “Bury you shall bury him on that same day” or if this is a proper source for a biblical mitzva to inter the deceased in the ground. Rambam Sefer Hamitzvos, Chinuch (537), Shulchan Aruch (Y.D. 362: 1) and most Poskim maintain burial is a biblical mitzva (Nishmas Adam, Gesher Hachaim 1: 16: 1and 2:12: 1 and Sdei Chemed – K’lalim 100: 39), however, some disagree (See Gesher Hachaim, ibid. See question 645 in this forum).
Chacham Tzvi (3) writes that the source for being buried at kever Yisroel or a Jewish cemetery, seems to emerge from the inherent need to honour the deceased, implied in the mitzva itself (“You shall not leave his body on the pole overnight” ibid). Kavod hames, showing proper respect to the dead, has always been a deeply-rooted tradition within the Jewish people. In Halacha, this concept finds its expression in the requirement of a speedy burial;in the waiver of various rabbinic restrictions on Shabbos and Yom Tov (O.H. 311 – 526) and laws against autopsy. This gives rise to the halachos of not inhuming the righteous beside the sinful, on a plot that does not belong to the deceased or in an unfitting place. Chacham Tzvi and others permit the desecration of exhuming the body for reburial in a kever Yisroel (See: Lev Aryeh 32).
Igrois Moishe (Y.D. 4: 56) maintains that it is also a biblical obligation to be buried in a Jewish cemetery, as a Halacha L’Moshe M’Sinai, based on Sanhedrin (47a,) in regards to the different sections provided for burial of the sentenced to a death penalty. He addresses a question of priority: when the only way to bring the remains of a dear one to Kever Yisroel is by exhuming and cremating the corpse (as was the requirement in the Soviet Union, where no Jewish graveyards were allowed) and then exporting only the ashes to be reburied in an overseas Jewish cemetery, which takes precedence, Kever Yisroel or avoiding cremation? He rules that the burial of the corpse in the ground is most essential, and being buried in a non-Jewish cemetery is only an “Isuro B’ealmo.”
Poskim also amply address the extent of the great obligation and mitzvah of searching for the remains and even part of corpses to be brought to Kever Yisroel after the Holocaust. (M’emek Habocho 8 and 11, Veherim Haconen 65, Or Hamizrach p.72)

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a