The Official Website of Grand Ayatollah Makarem Shirazi

A deceased Muslim's body must be buried in a Muslim cemetery. If a deceased Muslim's body is buried in a non-Muslim cemetery. The body should be exhumed and reburied in a burial ground designated for Muslims, if possible, if there is no Muslim cemetery in that place, then a segregated place must be chosen for burial if possible, if it just causes too much trouble, then there is no problem in burying the body in a common cemetery. Burying a Muslim in a Muslim cemetery is obligatory upon the deceased guardian. However, if there is no guardian, or the Guardian is incapable, then it is the collective obligation Al-wājib al-kifā’ī of other Muslims to undertake the burial arrangement. Burying the body of a deceased Muslim with a coffin is permitted, however, the Islamic rituals pertaining to burial must be observed, including laying the body on its right side in a way that it faces the Qibla. If a deceased Muslim has no guardian in a non-Muslim country, or there is no access to the guardian to obtain his permission, then the Guardian's consent is no more needed, and it is the collective obligation of other Muslims to perform all the Islamic burial rituals.