Meriam Yahia Ibrahim Ishag, who grew up as a Christian and is facing execution in Sudan for marrying a man of the same faith as her's, has given birth to a baby girl in prison.

As global outrage mounts against the punishment, rights' group Amnesty International said Wednesday that more than 620,000 its supporters worldwide have joined "the myriad of voices calling for Meriam's release."

The baby was born Tuesday in the hospital wing at Omdurman Federal Women's Prison in North Khartoum and is said to be healthy the MailOnline reported.

The Mail said that Ibrahim has spent "the past four months shackled to the floor in a disease-ridden jail."

"Imprisoned Sudanese Christian Meriam Yahia Ibrahim has given birth to a baby girl five days early," Christianity Solidarity Worldwide reported.

"According to local sources, Mrs Ibrahim's husband Daniel Wani has yet to be granted permission to see his wife and newborn daughter, who are currently incarcerated in Omdurman Federal Women's Prison along with his 20 month-old son Martin, but has been informed that both mother and baby are well," said CSW in a statement Tuesday.

Speaking to MailOnline, her lawyer Mohaned Mustafa Elnour said: 'This is some good news in what has been a terrible ordeal for Meriam.

"I am planning to visit her with her husband Daniel later today [Tuesday]. I think they are going to call the baby Maya," said Elnour.

A court in Khartoum upheld her sentence after she refused to renounce her Christianity and the sentence will be imposed when they new-born girl is two-years-old. Before that she will face 100 whip lashes as part of her punishment for being a Christian.

The general secretary of the World Council of Churches, Rev. Olav Fykse Tveit,wrote to Sudan President Omar Hassan Ahmad Al-Bashir to "prevent the implementation of this unjust and unconscionable sentence."

Tveit wrote on May 23, "Whether Mrs Meriam Yahia Ibrahim Ishag was born of Muslim parents or Christian parents, such a sentence runs counter to the letter and spirit of the Sudanese Constitution."

He noted that according to the Sudanese constitution all citizens have the "right to the freedom of religious creed and worship."

UN EXPERTS ALARMED

A group of United Nations human rights experts earlier expressed alarm about the sentence and the European Union, the United States, global Christian leaders and human rights advocacy groups have strongly condemned it.

The U.N. experts said on May 19 that trial of the mother who was pregnant at the time of her trial with her second child did not comply with basic fair trial and due process guarantees, said the experts.

"This outrageous conviction must be overturned and Ms. Ibrahim must be immediately released," urged the U.N. experts. They also called on the Sudanese government to repeal all legislation that discriminates on the grounds of gender or religion.

"Choosing and/or changing one's religion is not a crime at all; on the contrary, it is a basic human right," said the experts.

They said Sudan should include the protection of the religious identity of minority groups and they urged mainly-Muslim northeast African country to comprehensively its justice system in compliance with international standards.

"Mrs Ibrahim was born in western Sudan to a Sudanese Muslim father and an Ethiopian Orthodox mother. Her father left the family when she was six years old and she was subsequently brought up as a Christian by her mother.

"The case against Mrs Ibrahim began after Sudanese authorities were made aware of her marriage to Daniel Wani, a Christian with dual American and Sudanese citizenship," CSW said.

It quoted a Morning Star news report that Mrs Ibrahim testified before the court on March 4 that she is a life-long Christian, producing as evidence her marriage certificate ,where she is classified as Christian.

It said three potential witnesses from western Sudan who went to court to testify of Mrs Ibrahim's lifelong adheretnce to Christianity were prevented from giving evidence.