The British government denied Tuesday that a leaked memorandum at the heart of a contentious trial contained a threat by President Bush to bomb Al Jazeera, the Arabic television station. The government had previously withheld substantive comment on a report in The Daily Mirror last year that the memo said Mr. Bush made the threat in a private conversation with Prime Minister Tony Blair at the White House in April 2004 – a time when American commanders in Iraq were publicly critical of Al Jazeera’s coverage of the war. Full Story