Police in Lebanon have arrested the radical Muslim cleric, Omar Bakri Muhammad, several days after a military court sentenced him to life in prison.
He was tried in his absence, accused of forming a militant group to weaken Lebanon's government.
Omar Bakri Muhammad was born in Syria and also holds Lebanese nationality.
He lived in the UK for 20 years then travelled to Lebanon in 2005 amid a media storm over the London bombings. The UK excluded him from returning.
The British government said his presence was "not conducive to the public good".
Lebanese security officials told news agencies that Bakri Muhammad had been arrested at his home in the northern city of Tripoli.
"He is currently being transferred to Beirut," an official told the news agency AFP.
Correspondents say it was not immediately clear why the authorities did not arrest Bakri Muhammad earlier.
He was among 54 people sentenced to varying terms of imprisonment in trials of militants who fought the Lebanese army in 2007.
He was convicted of membership of an armed group aiming to commit "terrorist acts" and plotting to kill Lebanese soldiers.
Speaking to reporters after the sentence was handed down he said he would "not spend one day in prison".
"I will not hand myself in to any court. I do not believe in the law in Britain as in Lebanon," he said.
Bakri Muhammad ran a radical Islamist group, al-Muhajiroun, from north London until it was disbanded in 2004.
He provoked outrage after the London bombings in July 2005 by saying he would not inform the police if he knew Muslims were planning such attacks.
He left the UK soon afterwards on what he described as a holiday to see his mother in Beirut, but while he was abroad the British government used its powers to ban him from returning.