As the FBI sought nearly 400 people for questioning in the Sept. 11 terrorist attacks, Attorney General John Ashcroft said Tuesday that individuals with possible links to the hijackers who terrorized the nation obtained or tried to obtain licenses to transport hazardous materials.

Video: Ashcroft Asks for Tools to Fight Terrorism

"Our investigation has uncovered several individuals, including individuals who may have links to the hijackers, who fraudulently obtained or attempted to obtain hazardous-material transportation licenses," Ashcroft said.

Ashcroft issued the new warning as federal prosecutors worked to build a criminal case involving identification cards for five of the now-dead hijackers. One man was charged with aiding the hijackers.

New Developments

In France, anti-terrorist police detained at least four people early Tuesday in connection with a planned attack on the U.S. Embassy in Paris and other U.S. interests in France. Seven people already were in custody in France in connection with the alleged plot.

The FBI, meanwhile, dropped a material-witness warrant against a Texas doctor who had been detained. Al-Badr Al-Hazmi had been held in New York as a material witness in the Sept. 11 attacks. Government officials confirmed Tuesday that he was released and was returning to Texas.

A Saudi national, Al-Hazmi, 34, was doing a medical residency in radiology at University of Texas Health Science Center. He had been working at a military hospital located on Lackland Air Force Base in San Antonio in the days before the attacks.

Five Middle Eastern men were detained early Tuesday in Wynne, Ark., for questioning by the FBI and immigration authorities, said Cross County Sheriff Ronnie Baldwin. The five were stopped for speeding in a small town located in a heavy agriculture area.

Suspect Charged With Aiding Hijackers

Federal prosecutors worked to build a criminal case involving identification cards for five of the now-dead hijackers. One man was charged with aiding the hijackers.

The government said Herbert Villalobos accompanied Abdul Aziz Al Omari and Ahmed Saleh Al Ghamdi to a lawyer's office in Virginia on Aug. 2 to help the two suspected hijackers obtain state identity cards.

When shown photos of the hijackers by the FBI, Villalobos recognized three other suspects "believed to have commandeered American Airlines Flight 77" from Washington Dulles International Airport that crashed into the Pentagon, according to court documents. Villalobos said Hani Hanjour, Salem Al Hazmi and Majed Moqed were at the Arlington, Va., office of the state Department of Motor Vehicles on Aug. 2, just as Al Omari and Al Ghamdi were.

"Virginia DMV records ... show that all five men did in fact conduct various transactions relating to Virginia identification cards at the Arlington DMV," said a seven-page affidavit by an FBI agent.

The affidavit did not say whether the five used the IDs to become ticketed passengers aboard the doomed flights, which crashed in New York City and Pennsylvania.

The FBI says Al Omari was aboard American Airlines Flight 11 that struck the north tower of the World Trade Center.

Al Ghamdi was aboard United Flight 175 that hit the trade center's south tower. Villalobos was charged with unlawfully signing a Virginia residency form for Al Omari. He was being detained at an undisclosed location. A hearing is set for Wednesday morning.

Crop-Dusters Fly Again

The FBI has advised local police to be on the lookout for anything suspicious regarding crop-dusting aircraft, Ashcroft told a Senate hearing.

One of the hijackers had visited a Florida crop-dusting company several times in the weeks before the attacks and had sought a government loan for a crop-dusting plane.

Such reports have raised fears the small farm planes could be used in a biological or chemical attack. All crop-dusting planes were grounded Sunday and Monday as a precaution. The grounding was lifted early Tuesday.

Robert Epling of Community Bank of Florida said he has been told that Mohamed Atta, one of the suspected hijackers, sought a USDA loan for a crop-duster. The USDA is a tenant in the bank, which checked its files about Atta at the request of the FBI.

"We understand he was turned down" at the USDA "and they referred him to us," said Epling. A loan officer at the bank remembered a phone call from someone inquiring about crop-dusters, an unusual request because there are so few of the planes left in the area, Epling said. Nothing came of the inquiry from the unnamed person.

James Lester, an employee of South Florida Crop Care in Belle Glade, told the FBI that Atta was among the men who in groups of two or three visited the crop-dusting firm nearly every weekend for six or eight weeks before the attacks.

Atta was a persistent questioner and "I recognized him because he stayed on my feet all the time. I just about had to push him away from me," Lester said.

More than 6,900 people are missing and presumed dead from the attacks, in which Saudi exile Usama bin Laden has been named the leading suspect.

Ashcroft said 352 people have been arrested or detained in the investigation and 392 others who "we think ... have information that could be helpful" were being sought for questioning.

The Associated Press contributed to this report.