Al-Qaeda has regrouped in its Pakistani "safe haven" and is determined to inflict mass casualties through new attacks on the United States, a US intelligence report said on Tuesday.
Osama bin Laden's extremist group remains bent on acquiring weapons of mass destruction, including nuclear and biological arms, "and would not hesitate to use them" if it develops the capability, the report said.
Outlining "key judgements" by the US intelligence community on the terrorist threat to the United States, the report conclude that Al-Qaeda is gaining strength in lawless zone of Pakistan in the border with Afghanistan.
"As a result, we judge the United States currently is in a heightened threat environment," said the report, which came nearly six years after the September 11, 2001 attacks in which some 3,000 people were killed.
That conclusion from the report, which was leaked to the US press last week, has already prompted angry reactions from Democrats who accuse President George W Bush of making the United States more vulnerable by invading Iraq.
The report issued by the office of national intelligence director Mike McConnell said "Al-Qaeda in Iraq" has become "the most visible and capable affiliate" of Bin Laden's network with an intent to attack the United States.
"We assess the group has protected or regenerated key elements of its Homeland (US) attack capability, including a safe haven in the Pakistan Federally Administered Tribal Areas, operational lieutenants, and its top leadership," the report said.