Britain barred hard-line Muslim cleric Omar Bakri Mohammed on Friday from returning to the country, part of a government crackdown on Islamic preachers it fears inspire bombers such as those who attacked London in July.
Syrian-born Bakri, 46, left Britain for Lebanon on Saturday, saying he was going on holiday, after Prime Minister Tony Blair pledged to silence Islamists who glorify violence.
Bakri was detained for questioning in Beirut on Thursday but was released on Friday, Lebanese security officials said. Judicial sources said investigators had found he had not broken any laws.
A British Home Office spokeswoman said: "We don't feel he's conducive to the public good." Family members - including his wife, children and grandchildren - were free to remain.
The ban follows a campaign by Britain's tabloid media to oust the cleric, who has said he would not inform police if he knew Muslims were planning to bomb trains in Britain and supported attacks on UK troops in Afghanistan and Iraq.
Blair vowed to deport or exclude foreign nationals who encouraged or condoned terrorism after four British Muslim bombers killed themselves and 52 other people in attacks on London's transport system on July 7.
Britain on Thursday detained 10 people, including the alleged spiritual leader of al Qaeda in Europe, Jordanian national Abu Qatada, and pledged to deport them.
Jordan said on Friday it had not yet decided whether to ask Britain to extradite Qatada, sentenced in his absence to life imprisonment by an Amman court for a 1998 terrorist plot.
The government this week signed an agreement with Jordan that London says will protect deportees from ill treatment. It is seeking similar agreements with countries such as Algeria and Lebanon but rights campaigners say the assurances are worthless.
TERRORISM LINKS?
Bakri has lived in Britain since 1986. He used to live in Lebanon and has Lebanese citizenship.
The bearded cleric was involved with the British branch of the radical group Hizb ut-Tahrir and was closely linked to al Muhajiroun, which won notoriety for celebrating the September 11, 2001, attacks in the United States.
Britain has said it will ban Hizb ut-Tahrir and the successor group to the now defunct al Muhajiroun from operating in the country. Bakri says he is no longer involved with either.
Anjem Choudary, former head of al Muhajiroun and a close associate of Bakri, said the move contradicted the values of freedom of speech and democracy that Britain espoused.
"This is indicative of the oppressive nature of the British regime, who say they uphold certain values," he told Reuters.
The Muslim Council of Britain welcomed the ban, saying Bakri had "contributed to the demonising of ordinary British Muslims".
Some of Blair's anti-terrorism measures have angered civil liberties campaigners who fear they erode human rights and renege on international human rights commitments.
Blair has said he will override human rights laws if necessary in order to deport foreign nationals.
Senior government minister Lord Charles Falconer said Britain may reform laws to compel judges to give national security equal weight to human rights in deportation cases.
Judges have thwarted past government efforts to deport foreign nationals on the basis the European Convention on Human Rights - enshrined in Britain's 1998 Human Rights Act - guarantees deportees freedom from torture or ill treatment.
"I want a law which says the home secretary, supervised by the courts, has got to balance the rights of the individual deportee against the risks of national security," Falconer, head of the judiciary, told BBC Radio.