British police and immigration officers have detained 10 foreigners on grounds they pose a threat to national security. The Home Office says they will be deported.
The round ups came early Thursday around London, Birmingham and Leicester.
Home Office Minister Helen Blears says the action stems from heightened security concerns following the July 7 attacks on London's transit system that killed 52 passengers, as well as the four British Muslim bombers.
"We had the bombings on the 7th of July," she said. "Clearly, our national security is of the utmost importance now. And where we've got foreign nationals in this country whose presence is not conducive to the public good, then I believe they should be deported with proper assurances."
She says those detained will have legal representation, and can fight the deportation order in British courts.
But British human rights activists are challenging the action. Shami Chakrabarti of the civil rights group Liberty says the government should prosecute the foreigners if the danger is so real.
"I've always been of the view that, if people are dangerous terrorists, they should be prosecuted and convicted and incarcerated, rather than shuffled off around the globe, possibly to come back or peddle their hate and plot against the UK from abroad," she said.
Government sources say one of those detained is Abu Qatada, a Muslim cleric wanted in his native Jordan to serve a life sentence in connection with a bombing campaign.
British officials have described Abu Qatada as the senior spiritual adviser in Europe for the al-Qaida terrorist network.
Britain and Jordan concluded an extradition agreement Wednesday by which terror suspects can be sent back to Jordan with a pledge they will not be executed or tortured. Critics say there is no way to properly monitor the accord.
In other developments, authorities in Lebanon have detained a British-based Muslim cleric who last week said that, if he learned of another terrorist bomb plot in Britain, he would not tell police.
The cleric, Omar Bakri Mohammed, arrived in Beirut Saturday, a day after British Prime Minister Tony Blair announced a crackdown on radical Muslim preachers.
In court action, 11 people accused of terrorism-related charges appeared at legal hearings in London Thursday. Most are accused of hiding the whereabouts of the four prime suspects in the July 21 attempted bombings of London's transport grid.
Among those who appeared was Haroon Rashid Aswat, who faces extradition to the United States, where he is charged with plotting to set up a terrorist training camp. A judge has ordered him held without bail until his next court date on September 8.