David Cameron has urged the Sudanese government to lift the "barbaric" death sentence handed to a woman for marrying a Christian.
The Prime Minister joined Ed Miliband, Nick Clegg and Tony Blair in condemning the treatment of Meriam Ibrahim - who gave birth to a baby daughter this week while shackled in her cell.
Mr Cameron said he was "absolutely appalled" when he heard about the plight of the 27-year-old.
"The way she is being treated is barbaric and has no place in today's world," he told The Times.
"Religious freedom is an absolute, fundamental human right.
"I urge the government of Sudan to overturn the sentence and immediately provide appropriate support and medical care for her and her children.
" The UK will continue to press the government of Sudan to act."
Ms Ibrahim was raised a Christian by her mother and has refused to renounce the faith.
However, a court ruled earlier this month that she is Muslim because that was her father's faith.
Her Christian marriage was annulled and she was sentenced to 100 lashes for adultery and death by hanging for renouncing Islam.
Sex outside a "lawful relationship" is regarded as adultery under Sudanese law.
Former PM Mr Blair described the case as a "brutal and sickening distortion of faith".