The confusion caused by Abu Qatada's appeal against his deportation means he could be released on bail within weeks.
Home Secretary Theresa May has insisted that the application by the radical cleric's lawyers to prevent him being sent to Jordan should be thrown out by the European Court of Human Rights (ECHR) because it missed a three-month appeal deadline.
However, Labour has released advice from the research department of the Council of Europe - which is responsible for the court - suggesting it may have just beaten the deadline. Confusion over the appeal could lead to Qatada being back on British streets in just two or three weeks.
Mr Justice Mitting, the British special immigration appeals commission judge, returned Qatada to jail this week after a rapidly convened court hearing found deportation was imminent and the chance of Qatada trying to abscond had increased. But he said if it is "obvious" in two or three weeks that deportation is "not imminent" he will reconsider bail.
The revelation came as the Government faced further embarrassment over the case when a note, sent to the House of Commons Library, emerged that appeared to back the Qatada team's appeal timings. It was signed by Nathalie Chene of Secretariat of the Committee of Ministers Council of Europe.
It stresses that the final decision on whether the appeal is admissible now rests with a panel of five judges from the court's Grand Chamber.
Earlier, in the Commons, Mrs May was adamant that the appeal deadline had passed 24 hours earlier at midnight on Monday - April 16. She declared: "The Government has written to the European Court to make clear our case that the application should be rejected because it is out of time."
She acknowledged, however, that proceedings would have to be put on hold while the Grand Chamber panel came to a decision on the admissibility of the appeal. "They are the only final arbiters of what the deadline was," she said.
Pressed by Labour former home secretary Alan Johnson, she said that she took full responsibility for any error by the Government. "I, of course, take responsibility for decisions that I have taken. This is not a question of what officials have done. I take full responsibility," she said.
Shadow home secretary Yvette Cooper called for Mrs May to "get a grip" on the "farcical" situation. Speaking on BBC One's Question Time, she said: "The Home Secretary needs to get some answers pretty quickly and she also needs to get a grip on this shambles and sort it all out."