Al Qaeda is still the top threat for the United States, despite its weakened state, the FBI plans to tell U.S. lawmakers next week.

The terrorist network accused of carrying out the Sept. 11 attacks is also getting "varying degrees of support" from other Muslim extremist groups, who are engaged in a "jihad" or holy war on the United States and its Western allies, a government official familiar with the classified report said Wednesday.

Next week, FBI Director Robert Mueller is handing over the bureau's first national assessment to the House and Senate Intelligence Committees, more than two years after it was originally promised to Congress. Mueller, who began working just a month before the Sept. 11 attacks, has been criticized for the delay in getting to Congress the assessment, which has since been revised and rewritten.

The central conclusion of the report is that "Al Qaeda led by Usama bin Laden remains, for the foreseeable future, the most serious threat against the United States."

Al Qaeda operatives around the globe continue to plan large-scale strikes against the United States, and are seeking chemical, biological, radiological and nuclear weapons, the report says, citing various U.S. intelligence sources.

Evidence of Al Qaeda's undiminished power to conduct a large-scale attack includes the October nightclub bombing on the Indonesian island of Bali that killed nearly 200 and November attacks on a resort and airliner in Kenya.

The Kenyan attacks occurred nearly simultaneously. A vehicle packed with explosives plowed into a hotel, killing 15 people. Minutes earlier, unidentified assailants fired two missiles at an Arkia Airlines Boeing 757, narrowly missing the charter aircraft as it was taking off from Mombasa airport with Israeli tourists returning to Tel Aviv.

The "soft targets," ones that are particularly hard to anticipate, like the Bali bombing, makes Al Qaeda extremely dangerous despite its ouster from Afghanistan.

German Interior Minister Otto Schily, his nation's top counterterrorism official, agrees.

He said Wednesday that the "strength of Al Qaeda groups is as high as it was before Sept. 11, maybe also a little bit more than before" and "the threat has dimensions that are really dangerous."

Despite the warning, which comes as Muslims prepare for their annual Hajj, or pilgrimage to Mecca, the U.S. government has not raised the national terror alert system's rating.

It now stands at yellow, or elevated, which is the middle tier in a five-color system.

Gordon Johndroe, spokesman for the Homeland Security Department, said the threat level is evaluated daily and there are no immediate plans to raise the threat level.

"We remain concerned about the continued Al Qaeda activity overseas as well as Al Qaeda sympathizers here in the United States," he said. "Should additional information and analysis develop requiring the threat level to be raised, we will keep the American public informed as always."

The FBI is taking action to improve its counterterrorism efforts, such as enhancing its intelligence analysis abilities, focusing more agents on fighting terrorism and upgrading its computer capabilities, the report states.

The Associated Press contributed to this report.