Latest reports suggest that the Christian Sudanese mother-of-two who was sentenced to death for apostasy, released, and then detained at the airport yesterday, has been freed once more.

Meriam Ibrahim was sentenced to 100 lashes and death by hanging on May 11. Though she was bought up as a Christian her whole life, Ibrahim was found guilty of converting from Islam and was also accused of adultery after marrying a Christian man - a union deemed invalid under Sharia law.

Her punishment gained international attention, and campaigners from all over the world called on the Sudanese government to allow Ibrahim to walk free. Her shock release from prison on Monday was thus welcomed after the courts found her to be innocent of all charges.

However, the BBC reported yesterday that Ibrahim was arrested and taken into custody at the Khartoum airport while trying to leave the country and fly to the US, where her husband – Daniel Wani – is a citizen. He and their two children were allegedly detained alongside Ibrahim.

Ibrahim's lawyer, Eman Abdul-Rahim, later confirmed to the BBC that the family's travel documents were being questioned, and it became apparent that they were being held on suspicion of fraud.

The Independent reported late last night, however, that Ibrahim has once again been freed by the Sudanese authorities.

Spokeswoman for the US State Department, Marie Harf, said that the family had been "temporarily detained for several hours over questions related to their documents," but that American officials had been assured they were safe.

A top Sudanese official had earlier told the BBC that Ibrahim was using emergency South Sudanese papers to leave Sudan, and must obtain a valid passport and exit visa before she would be allowed to leave the country.

Former BBC Sudan correspondent, James Copnall, has suggested that Ibrahim's re-arrest may have been an attempt by Sudan's National Intelligence and Security Service to "flex...its muscles".

"It is very possible that NISS did not like the decision to release Meriam Ibrahim, and re-arresting her and her family was a way of making this point to the rest of the Sudanese government," Copnall speculates.

"It is also conceivable that one part of NISS accepted Mrs Ibrahim's release, while another section was not happy with it. Mrs Ibrahim's release and re-arrest simply underline the fact that there are many decision-makers in Sudanese politics, and they do not always agree with each other."

Persecution charity Release International yesterday welcomed Ibrahim's release, but warned that she is still at risk from "vigilantes" and that religious persecution in Sudan is on the rise.

"We're delighted Meriam has been released, but it should never have come to this," Release Chief Executive, Paul Robinson, said in a statement.

"Religious coercion - persecution by another name - is already getting worse for Christians in Sudan, despite the constitution. The authorities are becoming more rigid in their enforcement of Islamic law. They have demolished churches and deported Christians. And if it hadn't been for an international outcry, they might have taken the life of this woman.

Robinson continued: "We urge Sudan to continue to protect the religious freedom guaranteed under its interim constitution.

"Those guarantees must now be firmly enshrined in the forthcoming constitution and in law. And we call on the authorities to do all in their power to protect Meriam and her family."