U.S. Attorney General John Ashcroft said on Tuesday suspects potentially linked to Sept. 11 attacks on the United States obtained licenses to transport hazardous materials, and he urged the public to be on alert. 
"Today I can report to you that our investigation has uncovered several individuals, including individuals who may have links to the hijackers, who fraudulently have obtained or attempted to obtain hazardous material transportation licenses," Ashcroft told the U.S. Senate Judiciary Committee. 
"Given the current threat environment, the FBI has advised all law enforcement agencies to remain alert to these threats." Ashcroft said. 
Nearly 7,000 people have been reported missing or dead after attackers hijacked four commercial airliners on Sept. 11, smashed two into the World Trade Center in New York and another into the Pentagon near Washington. The fourth plane crashed in rural Pennsylvania. 
Although, the U.S. government lifted a two-day ban on flights by crop-duster planes on Tuesday -- imposed because of concerns the aircraft could be used in chemical or biological weapons attacks -- Ashcroft said the nation must not let its guard down on this or other fronts. 
"And I urge Americans to notify immediately the FBI of any suspicious circumstances that may come to your attention regarding hazardous materials, crop-dusting aircraft or any possible terrorist threat," he said. 
A senior U.S. Justice Department official told reporters about 20 individuals have been charged or arrested in the past two weeks with fraudulently obtaining a commercial license to haul hazardous materials. 
The official said not all 20 were witnesses or wanted for questioning in connection with the investigation into the hijacked plane attacks. The official said the 20 had used false documents to get the licenses. 
Ashcroft issued his update as he made the case on Capitol Hill for the second time in as many days for Congress to quickly approve new laws proposed by U.S President Bush's administration to help combat terrorism. 
"The American people do not have the luxury of unlimited time in erecting the necessary defenses to future or further terrorist attacks," Ashcroft said. "Terrorism is a clear and present danger to Americans today." 
In the wake of the attacks Ashcroft wants Congress to give law enforcement officers expanded powers to tap telephones, conduct searches, seize assets and detain suspects. 
While there is broad agreement that a number of laws need to be toughened -- such as lifting a five-year statute of limitations on prosecuting crimes of terrorism and formally making it a crime to harbor terrorists -- many legislators fear several of Ashcroft's other proposals would violate civil liberties. 
Critics complain about provisions that would allow indefinite detention, permit searches without notification of the targets and broaden the definition of terrorism to the point where convictions could be made merely on grounds of association rather than any specific activity. 
During a trip to FBI headquarters on Tuesday, Bush defended his administration's anti-terrorism package. 
"Ours is a land that values the constitutional rights of every citizen and we will honor those rights of course," Bush said. "But we're at war ... and in order to win the war we must make sure the law enforcement men and women have got the tools necessary, within the Constitution, to defeat the enemy." 
Vice President Dick Cheney, during a Capitol Hill luncheon meeting with Senate Republicans, said Congress should aim to pass an anti-terrorism bill by the end of next week, a Republican aide said. 
Senate Judiciary Committee Chairman Patrick Leahy, a Vermont Democrat, reaffirmed his vow on Tuesday to work with Ashcroft to craft a package "as soon as possible" that helps crack down on terrorism without infringing on civil liberties. 
"We cannot allow terrorism to prevail by curtailing our constitutional democracy or constricting our freedoms," Leahy said. 
Leahy said, "We are working to be in position without the passage of much time to pass significant legislation containing those consensus items." 
Leahy said he intends to reach out to House Judiciary Committee Chairman James Sensenbrenner, a Wisconsin Republican, to forge a bipartisan accord. 
Sensenbrenner had planned for his committee to report out Ashcroft's proposed measure on Tuesday. But he postponed consideration for a week following a hearing on Monday where Republicans and Democrats voiced a number of objections. 
