The Government is locked in dispute with lawyers representing the alleged terrorist agitator Abu Qatada over the meaning of "three months" - arguing that he has missed a deadline for an appeal against his extradition to Jordan.
The Home Office claims his appeal to the Grand Chamber of the European Court of Human Rights (ECHR) , lodged on Wednesday, is 24 hours too late, while it tries to stop him putting another road block on the route to his expulsion from the UK.
Home Secretary Theresa May told Sky News: "This is a delaying tactic from Abu Qatada and his lawyers.
"I am not at all surprised he's attempting to delay these proceedings.
"We have a very strong case for deportation... and of course it was only several hours after he and his lawyers had seen the strength of our case, of the Government's case, that they decided to make this referral."
She continued: "We will wait to see the decision of the European Court. Then we will resume deportation.
"I recognise the frustration that the British public have... but I think it is right that we follow the proper, legal processes.
"I am also clear that we have the case now to deport Abu Qatada to Jordan."
Prime Minister David Cameron later told reporters: "I am absolutely clear, the entire Government is clear, and frankly, I think the country is clear, that this man has no right to be in our country.
"He is a threat to our security, he has absolutely no further call on our hospitality, and he should be deported.
"That is what we are determined to achieve, no matter how difficult it is, no matter how long it will take. It will be done."
However, shadow home secretary Yvette Cooper has called on Mrs May to address the Commons to "clear up this shambles" and inform MPs on the latest developments.
"I don't think the Government should give Abu Qatada any legal loopholes, or create any legal loopholes, that he and his lawyers can take advantage of," she said.
"That's why I think this confusion and chaos over what date the deadline is really matters.
"The Home Office should have contacted the European Court to get the dates agreed in advance so there couldn't be any opportunity for Abu Qatada or his lawyers to do this."
On Monday, Mrs May announced that his "deportation might still take time - the proper processes must be followed and the rule of law must take precedence".
But she appeared to have been advised that his opportunity to appeal against the January 17 ruling from the European Court of Human Rights had passed.
That ruling found that the UK could not extradite Qatada to face terrorism related charges in Jordan because there was a risk of his being tried using evidence gathered from two other witnesses under torture.
But, crucially for the Government, the ruling accepted the principle that if the UK could get assurances from Jordan that evidence obtained under torture would not be used, and that Qatada would not face the death penalty or other sanctions which are illegal in Europe, he could be deported.
Jordan agreed to offer these assurances - which triggered the UK deportation process.
Qatada, once described as Osama bin Laden's representative in Europe, was already expected to appeal against this once the proceedings got underway following his re-arrest in London on Tuesday . These could have dragged on for months.
The 51-year-old has fought off every attempt to deport him to Jordan, where he has been convicted in absentia of terror charges in 1989.
The latest efforts to send him to the Middle East were the result of direct appeals by the British to King Abdullah II of Jordan.
Now a panel of judges at the European Court will take "up to several weeks" to decide firstly whether his lawyers made the deadline for the appeal or not, and then whether to advance it to the Grand Chamber.
The move comes as the 47 member nations of the Council of Europe prepare to meet in Brighton on Thursday for talks aimed at reforming the court and the types of cases it hears.
Qatada, who was born in Bethlehem then part of Jordan, featured in hate sermons found on videos in the flat of one of the September 11 bombers.
A Home Office spokesman said: "Qatada has no right to refer the case to the Grand Chamber of the European Court of Human Rights, since the three-month deadline to do so lapsed at midnight on Monday night.
"His case should be heard in British courts, as the Home Secretary outlined to Parliament. In the meantime, he remains in custody."
A spokesman for the Prime Minister said that the Government would oppose any bail application which followed from the latest attempt by Abu Qatada to appeal "vigorously".