MIAMI (Reuters) - Seven people arrested in Miami planned attacks on the landmark Sears Tower in Chicago and other buildings as part of a pledge to al Qaeda to wage war against the United States, U.S. prosecutors said on Friday.

An indictment handed down against the men by a grand jury in south Florida said they sought to gain support from Osama bin Laden's al Qaeda in order to destroy FBI buildings in the United States. At least one of them also plotted to blow up the 110-story Sears Tower in Chicago, it said.

The men, named as Narseal Batiste, Patrick Abraham, Stanley Grant Phanor, Naudimar Herrera, Burson Augustin, Lyglenson Lemorin and Rotschild Augustine, were due to appear in a Miami magistrate's court later on Friday.

They were arrested on Thursday after heavily armed FBI agents and other law enforcement agencies swooped on a warehouse in one of Miami's poorest neighborhoods, Liberty City, a predominantly black area that has witnessed some of Miami's worst race riots.

A man identified as a member of the "Seas of David" religious group told CNN on Thursday that five of his fellow members were among those arrested and that they had no connection to terrorists.

"We are not terrorists. We are members of David, Seas of David," said the man, identified as Brother Corey. He said the group had "soldiers" in Chicago, but reiterated it was peaceful movement. The indictment said all of the defendants also referred to themselves as "Brothers."

U.S. Attorney General Alberto Gonzales was to participate in an FBI news briefing in Washington on the arrests at 10:30 a.m. EDT/1430 GMT and more details were to be given at another FBI news briefing later Friday in Miami.

A parade through Miami to celebrate the victory by the Miami Heat team in the National Basketball Association championship, expected to attract about 200,000 people, was still due to go ahead on Friday and the authorities stressed that citizens were never at risk.

The defendants were given by an FBI informant, a law enforcement source said.

It was unclear what impact if any the arrests might have on public opinion ahead of mid-term congressional elections in November, and amid a deep slump in President George W. Bush's popularity and in public support for the Iraq war.