Washington ? Insurgent networks across Iraq are increasingly trying to acquire and use toxic nerve gases, blister agents and germ weapons against U.S. and coalition forces, according to a CIA report, and investigators said one group recruited scientists and sought to prepare poisons over seven months before it was dismantled in June.

U.S. officials say the threat is especially worrisome because leaders of the previously unknown group, which investigators dubbed the “Al Abud network,” were based in Fallujah in proximity to insurgents aligned with fugitive militant Abu Musab Zarqawi. The CIA says Zarqawi, who is blamed for numerous attacks on U.S. forces and beheadings of hostages, has long sought to use chemical and biological weapons against targets in Europe as well as Iraq.

An exhaustive report released last week by Charles Duelfer, the CIA’s chief weapons investigator in Iraq, concluded that Saddam Hussein destroyed his stockpiles of chemical and biological weapons in the early 1990s and never tried to rebuild them. But a little-noticed section of the 960-page report warns that the danger of a “devastating” attack with unconventional weapons has grown since the U.S.-led invasion and occupation of Iraq last year.

The Bush administration, which went to war primarily to disarm the Baghdad regime of suspected illicit stockpiles, has not previously disclosed that the insurgent groups that have emerged and steadily expanded since Saddam’s ouster now are seeking to develop their own crude supplies of such deadly agents as mustard gas, ricin and the nerve gas tabun.

Neither of the two chemists who worked for Al Abud had any ties to Saddam’s long-defunct weapons programs, and Duelfer’s investigators found no evidence that the group’s poison project was part of a “prescribed plan by the former regime to fuel an insurgency.”

For now, the leaders and financiers of the network “remain at large, and alleged chemical munitions remain unaccounted,” the report said. It added that other insurgent groups are “planning or attempting to produce or acquire” chemical and biological agents throughout Iraq, and warns that the availability of chemicals and munitions, as well as sympathetic former Iraqi weapons scientists, “increases the future threat.”