WASHINGTON (AP) _ The FBI has detained 49 people for questioning in the terrorist attacks, officials disclosed Monday as they pledged numerous federal agents would also fly commercial airlines for added safety.
Attorney General John Ashcroft announced the new sky marshals as he also pleaded with Congress to pass by week's end anti-terrorism laws that could assist the current investigation.
The changes would expand wiretapping and increase prison penalties for those who aid terrorists.
``We need these tools to fight the terrorism threat which exists in the United States and we must meet that growing threat,'' Ashcroft said.
FBI Director Robert Mueller disclosed that 49 people _ nearly double the number when the weekend began _ have been detained for questioning in the probe or because of questions about their immigration status.
Mueller also said there were a number of material witness warrants that have been issued for suspects, but he said the warrants were sealed. Officials previously disclosed two arrests.
Ashcroft said law enforcement officers believe there is a continuing threat because ``associates of the hijackers that have ties to terrorist organizations may be a continuing presence in the United States.''
He directed the U.S. Marshals Service to assign more than 300 deputies to assist FBI field offices in the probe, which has received 7,700 phone calls and 47,000 tips on the Internet.
The attorney general said a growing number of federal law enforcement agents from the Justice Department would be boarding commercial flights as air marshals. Typically, air marshals are armed.
Rep. John Mica, R-Fla., chairman of the House Transportation aviation subcommittee, said the first group of new air marshals would be transferred from existing federal law enforcement agencies to get them aboard flights quickly. More eventually will be hired.
``Each day as flights increase we will be adding additional enforcement officials ... as air marshals in addition to the heightened security on the ground,'' Ashcroft said.
Mueller also disclosed that at least two killings were possibly inspired by anti-Arab sentiment and he sternly warned against any vigilante attacks.
He said federal law enforcement is not singling out Arabs. ``We do not, have not, will not target people solely based on their ethnicity,'' he said.
Congressional leaders emerged from FBI headquarters Sunday saying they were pleased with the progress of the investigation, and the Justice Department disclosed that a federal grand jury in New York is working on warrants for material witnesses.
At least two arrests have been made to keep witnesses in custody; authorities said they won't disclose any others because of grand jury secrecy rules.
The first arrest was of a man at John F. Kennedy International Airport who had a fake pilot's license. No details were released on the second.
In regard to the wiretap legislation, suspicion of terrorism is not a valid legal reason currently to get a wiretap.
Ashcroft said wiretap authorization should be focused on the person rather than the phone he uses because with the advent of ``disposable telephones ... it simply doesn't make sense to have the surveillance authority associated with the hardware.''
Penalties for people who aid terrorists should be raised to at least the same level as the punishment for those who help people involved in espionage, Ashcroft said in a televised address from Camp David, Md., where he and other top national security officials met with President Bush. People who harbor terrorists now face five-year prison terms.
``Our effort is to develop all the information we can about terrorism, the terrorists and the terrorist networks that have inflicted this injury on the United States and this assault upon the people of the world, and to do everything we can to disrupt them and to put an end to their capacity,'' Ashcroft said.
An early expression of support came from Sen. Orrin Hatch of Utah, the ranking Republican on the Senate Judiciary Committee.
``We need to modernize our laws to make sure that no stone goes unturned in this investigation,'' Hatch said after the FBI meeting. He embraced the administration's proposal for nationwide jurisdiction of court orders authorizing law enforcement officials to identify telephones, computers, and other communications devices being used in terrorist act.
Senators including Richard Shelby, R-Ala., vice chairman of the intelligence committee, expressed satisfaction with the pace of the investigation after CIA and FBI briefings.