Police released one of 13 men arrested in an anti-terrorist sweep in London and towns north of the capital, as 12 others faced questioning Wednesday after a series of raids which authorities said were part of a continuing investigation.

The arrests brought complaints from the Muslim community that it was being targeted unfairly — a claim supported by a Parliamentary report released Wednesday.

Thirteen men, aged 19 to 32, were arrested in London, Bushey, Luton and in Blackburn in northwestern England. All were arrested "on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism," and were brought to London for questioning, the Metropolitan Police said.

One man, from London, was released without charge Wednesday, police said. Searches at several homes continued, they said.

Police released no details of the nationality and religious affiliation of those arrested, but news reports suggested that at least some of the suspects are of South Asian origin and are Muslims.

"There is a feeling in the community that they are being victimized," said Yasin Rehman of the Luton Council of Mosques (search). One of Tuesday's arrests was in Luton, 30 miles north of London.

Parliament's Joint Committee on Human Rights supported that complaint, and called for changes in the emergency laws enacted soon after the Sept. 11 attacks in the United States.

"There is mounting evidence that the powers under the Terrorism Act are being used disproportionately against members of the Muslim community in the U.K.," the committee reported.

Britain opted out of a part of the European Convention on Human Rights (search) to enact legislation to allow some suspects to be imprisoned without trial.

"If the threat from international terrorism is to continue for the foreseeable future, the committee considers that an alternative way must be found to deal with that threat without derogating indefinitely from important human rights considerations," the legislators reported.

The arrests did not appear to be linked to information Pakistani authorities recently said they had uncovered about threats to Britain and America.

Pakistan's information minister said Monday his country found plans for new attacks against the United States and Britain on a computer seized during the arrest last month of a senior Al Qaeda suspect wanted for the 1998 U.S. embassy bombings in East Africa.

Asked whether the Tuesday raids were linked to the recent Pakistani discovery, British police declined to answer directly, but noted that the investigation leading to the arrests had been underway for some time.

Police will have up to two weeks to hold the men arrested Tuesday before deciding whether to charge them.

British authorities say the threat from terrorism remains high, but they have not warned of any specific threat like that announced in the United States. The intelligence behind the latest U.S. terror warnings was as much as four years old, and law enforcement officials are trying to determine whether the plot was current.

Britain has arrested hundreds of people in anti-terrorist investigations since Sept. 11, 2001, but few convictions have followed.

The Home Office said in May that there had been 562 arrests, which resulted in 97 people being charged and 14 convicted. Nearly half — 280 people — were released without charge and no further action was taken.

"If these raids are successful and the police do find something, that is supportable. But in the last raids (in March) no one was charged or convicted and it gives them the feeling they are being targeted," said Rehman from the Luton Council of Mosques.

Vulnerable young people were being targeted by extremist groups, he said.

"There is high unemployment, predominantly among the Muslim community," he said.

"We should first address the social problems. We need to stop the breeding grounds and stop the recruitment," Rehman added.