BAGHDAD, Feb. 22 — American troops on a raid near Falluja discovered three car bombs under construction in a bomb-making factory that appeared intended to be used with chemicals, the chief American military spokesman in Baghdad said Thursday.

Five of the buildings raided by American forces were packed with munitions and chemicals, he said.

The discovery follows three gas attacks in the past month in which insurgents used truck bombs to deploy chlorine, a greenish gas that burns the skin and can be fatal after just a few deep breaths. The latest such bombing on Wednesday in southern Baghdad killed at least two people and wounded 32 others, many exhibiting symptoms of chlorine exposure.

The spokesman, Maj. Gen. William B. Caldwell IV, described the materials found in the raid as 65 propane tanks and ordinary chemicals, but he did not say any chlorine gas was found. He said the troops found “five complete buildings full of these various types of things to include car bombs that were being assembled and put together with propane tanks.

The insurgents’ recent use of chlorine gas in bombings appeared to be a new attempt to heighten fears among Iraqi citizens, he said on CNN.