WASHINGTON (AP) - Marking one month since the terror attacks, Attorney General John Ashcroft said Thursday that Americans should act as if another wave of terrorism could come at any time.

"It's likely that there are terrorists who want to be able to disrupt America," Ashcroft said. "We have to prepare ourselves."

Officials are warning that coded messages possibly buried in broadcast communications of Osama bin Laden or others in his terrorist network could be used to help launch more attacks. TV network executives said Wednesday they would screen and perhaps edit such tape before showing it.

As with his earlier calls for Americans to stay vigilant, Ashcroft did not convey any specific terrorist threats when he spoke on the morning talk shows. But he said people shouldn't let down their guard.

"I believe that we have to act as if terrorism can strike at any time," he said on ABC's "Good Morning America." Before Sept. 11, "We acted as if terrorists couldn't strike, in a lot of ways."

As U.S. bombs rained down on Afghanistan, European police were alerted to hunt for eight suspected terrorists linked to Osama bin Laden, U.S. officials said Wednesday.

In Washington, FBI agents met authorities from Germany, where aspects of the Sept. 11 attacks may have been planned and where at least three of the 19 suspected hijackers worked and studied.

Concern about new attacks rose when the White House asked TV networks to be careful about showing videotaped messages from bin Laden and his organization.

"At best, this is a forum for prerecorded, pretaped propaganda inciting people to kill Americans," White House press secretary Ari Fleischer said.

At worst, the broadcasts could contain signals to "sleeper" agents awaiting instructions to act, he added. "The concern here is not allowing terrorists to receive what might be a message from Osama bin Laden calling on them to take any actions."

On Tuesday, a top aide to bin Laden said in a videotaped message that the U.S. strikes on Afghanistan "have opened a new page of animosity between us and the forces of the unbelievers. We will fight them with every material we have."

Following a conference call with Bush's national security adviser, Condoleezza Rice, ABC, CBS, CNN, NBC and Fox agreed they would not broadcast transmissions from bin Laden's al-Qaida group without first screening and possibly editing them.

President Bush released pictures of 22 "most-wanted" terrorists, hoping television viewers and newspaper readers around the world would see them. The government was offering a reward of up to $5 million for the capture of anyone on the list.

"We list their names, we publicize their pictures, we rob them of their secrecy," the president said at FBI headquarters. The list included bin Laden and several people linked to the 19 hijackers who crashed planes into the World Trade Center towers and the Pentagon, and commandeered the airliner that crashed in Pennsylvania.

In Florida, federal authorities said Wednesday that a third person _ a 35-year-old woman _ has been exposed to anthrax and the case has become a criminal investigation.

While anthrax could be used in a terrorist attack, FBI agent Hector Pesquera said authorities had no evidence it was caused or created by a terrorist group.

Ashcroft said authorities have no evidence showing that the anthrax had been stolen from any laboratory. Officials cannot "announce any source of the anthrax," he said on NBC's "Today" show.

He said officials have investigated 30 or more anthrax scares around the county and none has panned out, except for the three at the supermarket-tabloid offices in Boca Raton.

At the Pentagon, the Defense Department said none of the suspected hijackers received training at U.S. military schools. Three hijackers have names similar to those who attended the schools, but a review of biographical data indicates they are not the same people, Army Lt. Col. Catherine Abbott said.

Abroad, Spanish investigators have told The Associated Press that Essid Sami Ben Khemais, a Tunisian arrested in April, met earlier this year with Mohamed Atta, one of the hijackers who hit the World Trade Center, and with members of an Algerian group now in Spanish custody.

Ben Khemais, who police believe was sent from Afghanistan to supervise bin Laden's terrorist operations in Europe, and five others arrested in Italy and Germany in April have been linked to an attack planned for January against the U.S. Embassy in Rome.

In June, Spanish police arrested Mohammed Bensakhria, an Algerian described as one of bin Laden's key people in Europe, and extradited him to France.

National Police Chief Juan Cotino said Bensakhria and other bin Laden deputies traveled to Spain earlier this year where they apparently issued orders to members of a suspected Algerian terrorist cell to attack U.S. interests in Europe.

Last month, police arrested six Algerians in raids in different parts of the country and confiscated videos and instruction manuals for bomb attacks.