The French secret service is believed to have refused to allow MI6 to give the Americans "credible" intelligence showing that Iraq was trying to buy uranium ore from Niger, US intelligence sources said yesterday.MI6 had more than one "different and credible" piece of intelligence to show that Iraq was attempting to buy the ore, known as yellowcake, British officials insisted. But it was given to them by at least one and possibly two intelligence services and, under the rules governing cooperation, it could not be shared with anyone else without the originator's permission.US intelligence sources believe that the most likely...