London, July 12: Foreign Secretary Jack Straw defended Britain's publication of a discredited charge that Iraq tried to get uranium from Africa, writing in a letter released today that the CIA expressed doubts about the allegation but did not say why. Straw said in the letter to the house of commons select committee on foreign affairs that Britain was unaware until recently that a US envoy went to Niger to investigate the claim and found it could not be substantiated. Britain made the accusation in a September dossier about alleged Iraqi weapons of mass destruction. It is now the subject of angry questions about how it ended up in US President George W Bush's state of the union speech in January. The White House has acknowledged the charge was false and bush said yesterday that the CIA had reviewed his address and did not raise any alarms. Bureau Report