A Sudanese court has given a 27-year-old woman until Thursday to abandon her Christian faith or face a death sentence, judicial sources have said.
Mariam Yahya Ibrahim Ishag, who was born to a Muslim father, was charged with apostasy, as well as adultery, for marrying a Christian man, something prohibited for Muslim women to do and which makes the marriage void.
The human rights group, Amnesty International, said Ishag was raised as an Orthodox Christian, her mother's religion, because her Muslim father was absent.
Ibrahim's case was the first of its kind to be heard in Sudan, the Reuters news agency reported. A final ruling will be announced on Thursday.
Sudanese rights activists sharply condemned the accusations and called on the Sudanese government to respect freedom of faith.
"The details of this case expose the regime's blatant interference in the personal life of Sudanese citizens," Sudan Change Now Movement, a youth group, said in a statement.
Western embassies in Khartoum also expressed "deep concern" over the case.
"We call upon the government of Sudan to respect the right to freedom of religion, including one's right to change one's faith or beliefs," the embassies of the United States, Canada, the United Kingdom and the Netherlands said in a joint statement.
The embassies urged Sudanese legal authorities "to approach Ms Mariam's case with justice and compassion that is in keeping with the values of the Sudanese people".
Speaking to the AFP news agency, Ahmed Bilal Osman, Sudan's Information minister, said: "It's not only Sudan. In Saudi Arabia, in all the Muslim countries, it is not allowed at all for a Muslim to change his religion."
President Omar al-Bashir's government is facing a huge economic and political challenge after the 2011 secession of South Sudan, which was Sudan's main source of oil.
A decision by Bashir last year to cut subsidies and impose austerity measures prompted violent protests in which dozens were killed and hundreds were injured.