British authorities detained seven foreigners Thursday for deportation as threats to national security, and the government backed a police proposal to hold terrorism suspects for as long as three months without charge.

Civil rights activists condemned the idea of increasing detentions from the current 14 days, as proposed in legislation unveiled Thursday by Home Secretary Charles Clarke to toughen anti-terrorism laws after the deadly July 7 bombing attacks on London commuters.

If approved by Parliament, the legislation also would outlaw "indirect incitement" of terrorism and "glorifying" violence -- provisions aimed at extremist Islamic clerics accused of seducing youths into militant activities.

The legislation would widen government powers to ban organizations if they support terrorism, make it an offense to publish or sell material that incites terrorism and outlaw attending terrorist training camps.

Prime Minister Tony Blair's government hopes to get the bill passed by the end of the year.

Since the July 7 bombings, which killed 52 people and the four presumed bombers, and failed bombings two weeks later, Blair has moved to tighten terrorism laws and crack down on Islamic extremists.

Last month, authorities detained 10 foreigners for deportation, including Abu Qatada, a radical cleric who previously had been described by Spanish officials as Osama bin Laden's "spiritual ambassador in Europe."

The government declined to say what prompted the detentions Thursday in London and Manchester or to disclose the names or nationalities of the seven men. It said they were being held under "powers to deport individuals whose presence in the U.K. is not conducive to the public good for reasons of national security."

A senior government official, speaking on condition of anonymity, said some of the seven had been suspects in a 2003 plot to make ricin, a deadly poison, but had been acquitted or had the charges against them dropped.

Gareth Peirce, an attorney who represented some of the defendants in the ricin case, was unavailable for comment, her office said.

In April, an Algerian man with alleged links to al Qaeda was the only one of nine suspects to be convicted in the ricin case. Kamel Bourgass was sentenced to 17 years in prison for allegedly writing recipes for making ricin.

The men detained Thursday have five working days to appeal the deportation order. The Home Office stressed they would not be deported until their home countries guaranteed they would not be abused or tortured after they returned.