<p>NORTHERN IRAQ (CNN) --U.S. forces have begun combing a bombed site in northern Iraq in search of chemical and biological weapons after airstrikes hit the facility this weekend, the top U.S. general said Sunday.</p>
<p>The complex is believed to be where the lethal poison ricin was produced for an alleged plot to attack London, England, that has since been foiled, said Gen. Richard Myers, chairman of the Joint Chiefs of Staff.</p>