Attorney General John Ashcroft said there is credible information that a terrorist attack in the United States may be imminent. "Credible intelligence from multiple sources indicates that al-Qaida plans to attempt an attack on the United States in the next few months. This disturbing intelligence indicates al-Qaida's specific intention to hit the United States hard," he said.

Mr. Ashcroft said statements from al-Qaida after the terrorist bombing in Madrid in March say it is 90 percent ready to carry out an attack.

But he says there is no information indicating where or when that could happen.

Source FBI A poster of individuals sought in connection with possible terrorist threats against the United States

The FBI has released the names of seven individuals accused of links to al-Qaida, including a U.S. convert to Islam, a Pakistani woman known as an al-Qaida operative who studied in the United States and two Africans indicted in the 1998 terrorist bombings of U.S. embassies in Kenya and Tanzania.

"They all are sought in connection with possible terrorist threats in the United States. They all pose a clear and present danger to America. They all should be considered armed and dangerous," said Mr. Ashcroft

Mr. Ashcroft would not say if intelligence agencies know for certain whether any of the seven or other terrorist suspects are currently in the United States.

At the White House, spokesman Scott McClellan said that possibility cannot be ruled out. "In terms of the possibility of terrorists being here in the United States, we have to work under the assumption there are terrorists here and the intelligence reporting we have seen from time to time there may well be people in place ready to carry out attacks," he said.

U.S. officials point to several events they say could be attractive terrorist targets - including the Republican and Democratic political party conventions, a summit of the Group of Eight and the presidential elections in November. However, previous terrorist attacks against U.S. interests have not necessarily been linked to major events.

But Department of Homeland Security chief Tom Ridge is playing down any need for public alarm. "We don't need to raise the threat level to increase our security," he said.