Radical cleric Abu Qatada has been arrested and told the Home Office will try to deport him, the BBC understands.
He is expected to appear at the Special Immigration Appeals Commission on Tuesday afternoon, when the home secretary will update MPs on his case.
The European Court of Human Rights blocked his deportation to Jordan in January, saying evidence obtained by torture might be used against him.
Ministers have been seeking assurances from Jordan this will not be the case.
The Home Office had previously said it was making “good progress” in obtaining those guarantees from Jordan, where he faces charges of plotting bomb attacks.
Home Secretary Theresa May travelled to Jordan in March for talks with the king and ministers on the case of the 51-year-old Palestinian-Jordanian, whom ministers have described as “extremely dangerous”.
She will make an emergency statement to the Commons on Tuesday about the cleric, who is regarded as a threat to UK national security.
BBC political correspondent Norman Smith said the fact that Mrs May had chosen to address the Commons indicated she had probably secured the necessary assurances.
A British judge had ended Abu Qatada’s six-year UK detention in February, weeks after the European Court of Human Rights blocked his deportation.
Shortly before the cleric was arrested, Conservative MP Peter Bone told the BBC the government should deport him and deal with any legal consequences afterwards.
“All the assurances the European court wanted are there,” he said.
“As the conditions are now met, he should be deported and there should be no hold-up. If his lawyers want to carry on [appealing] afterwards, that’s up to them.”
Abu Qatada has never been charged with any offence in the UK but British authorities have previously said he gave advice to those who aimed “to engage in terrorist attacks, including suicide bombings”.
He faces a re-trial in Jordan for plotting bomb attacks against American and Israeli tourists during the country’s millennium celebrations, offences he was convicted of in his absence.
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