KHARTOUM (AFP) - A Sudanese Christian who gave birth in prison after being sentenced to hang for apostasy has been freed, one of her lawyers said on Monday.

The case of Meriam Yahia Ibrahim Ishag sparked an outcry from Western governments and rights groups after a judge sentenced her to hang on May 15.

"Meriam was released just about an hour ago," Mohanad Mustafa told AFP on Monday afternoon.

"She's now out of prison," he said, but authorities will not issue the reasons for her release until Tuesday.

Born to a Muslim father and an Ethiopian Orthodox Christian mother, Ishag was convicted under Islamic sharia law that has been in force in Sudan since 1983 and outlaws conversions on pain of death.

Twelve days after the verdict, Ishag gave birth to a daughter at the women's prison in Khartoum's twin city of Omdurman.