Washington ? An American touted by Atty. Gen. John Ashcroft as a significant terrorism figure with plans to detonate a radioactive bomb is probably a “small fish” with no ties to al-Qaida cell members in the United States, law enforcement officials say.

The FBI’s investigation has produced no evidence that Jose Padilla had begun preparations for an attack and little reason to believe he had any support from al-Qaida to direct such a plot, said one of the officials, speaking on condition of anonymity.

U.S. officials now say Jose Padilla, shown in this undated file photo, is not the major terror suspect he was initially thought to be.

The official said Padilla is a “small fish” in the terrorism investigation, but someone authorities still believe warrants being detained.

Padilla, 31, is being detained in a military brig in South Carolina as an enemy combatant, a legal designation allowing the government to jail him without formal criminal charges. His attorney has argued in court that he is being held illegally and should be released.

Investigators have said they believe Padilla, a Muslim convert and a former Chicago gang member, ventured overseas in search of clerics connected to the most radical branch of Islamic fundamentalism.

In early June, Ashcroft announced from Moscow that Padilla was arrested at O’Hare International Airport in Chicago. Ashcroft’s deputies also convened a news conference in Washington.

“We have disrupted an unfolding terrorist plot to attack the United States by exploding a radioactive dirty bomb,” Ashcroft said, adding that the government’s suspicions about Padilla’s plans came from “multiple, independent, corroborating sources.”

Now, two law enforcement officials close to the case say there is no evidence a plot was under way. One had been “thought out as a possibility,” an official said.

Padilla’s attorney, Donna Newman, said the government was avoiding a court case because it has little evidence against him.

“What we could analyze from government statements is that they didn’t have sufficient evidence to charge him,” Newman said. “All they could do was allege that he was somehow involved in the talking stages of a plan and they didn’t even allege his role. And that is supposed to be enough to hold him without trial?”

Justice Department officials declined to comment on the matter Tuesday.