A federal judge denied bond Wednesday to six men accused of plotting to blow up Chicago's Sears Tower and conspiring to help Al Qaeda attack several federal buildings.

The six, who have pleaded not guilty, were arrested June 22 in Miami as part of an undercover FBI sting. They are accused of seeking to support what they thought was an Al Qaeda operative's effort to bomb FBI buildings in Chicago, Los Angeles, Miami, New York and Washington.

A seventh man arrested in the case and charged in Atlanta was also being held without bond.

U.S. Magistrate Judge Ted Bandstra ruled Wednesday that the men in Miami posed too great a risk to the community to be released.

"The charges against each of the defendants are serious charges and constitute counts of violence," Bandstra said, adding that it was "not relevant that the plans appear to be beyond the abilities of the defendants."

Officials say the group's ringleader, Narseal Batiste, 32, approached an acquaintance and asked the man to put him in touch with someone in the Middle East who might be able to finance their plan.

The acquaintance alerted the FBI, which helped connect Batiste with a man pretending to be an Al Qaeda contact, officials said. They said that the contact had the men swear an oath of allegiance to the terrorist group, but the men never had explosives or actual contact with the terrorist network.

In addition to Batiste, the Miami defendants in the case are Stanley Grant Phanor, Patrick Abraham, Naudimar Herrera, Burson Augustin and Rothschild Augustin. The man charged in Atlanta, Lyglenson Lemorin, was scheduled to be moved to Miami.

"The case is essentially something the government set up to knock down," said Batiste's attorney, John Wylie.

He and other defense attorneys argued that the government's case was overblown and suggested the informants baited Batiste into offering to help conduct surveillance of the federal buildings.

Wylie sought to have Batiste released until trial, arguing in a written request that he could find no other case in which the government provided a "sham" Al Qaeda representative to "create the basis for charges of terrorist conspiracy."

Nathan Clark, an attorney for Rotschild Augustin, said after the hearing that he was not surprised by the judge's decision, given the charges.

"But the government's case is not as strong as it appears," he said.

Each of the men faces four counts: two counts of conspiracy to provide material support to a foreign terrorist organization, and one count each of conspiracy to destroy buildings by explosives, and sedition against the U.S. government. The counts carry maximum sentences of between 15 and 20 years.

Several relatives of the men have denied that they were violent. They described the defendants as deeply religious men who studied the Bible and Islam.