The hijackers in Tuesday’s attacks likely had outside help on the ground, federal law enforcement officials said yesterday.

While no arrests have yet been made, U.S. Attorney General John Ashcroft said authorities have interviewed hundreds of people in connection with Tuesday’s attacks. In addition, several people were detained during security scares at New York’s newly reopened airports.

A number of people who could be involved in the plot were held overnight for having false identifications, Justice Department spokesperson Mindy Tucker said, although she declined to comment further.

On Wednesday, FBI agents raided a Boston hotel and detained three men, who were later released.

In an interview with ABC’s “Good Morning America” yesterday, Ashcroft said new information pointed to a widespread conspiracy involving as many as 50 people, including the 18 hijackers already identified. Each plane had four or five hijackers that probably had on-the-ground help, he said.

“[To have] operated with technical proficiency to target and to land an aircraft of that size with the deadly accuracy of these acts of war was something obviously that resulted from a complex organization with significant ground support,” Ashcroft said.

The special task force of 4,000 FBI agents, comprising the largest investigation in America’s history, was busy yesterday checking some of the leads garnered from the 2,055 calls to the FBI’s hotline and the 22,700 tips received from a special website set up for the investigation.

“Some of these leads have been helpful to the investigation,” Ashcroft said.