By Luke Baker LONDON, April 18 (Reuters) - The trial began in London on Wednesday of two men accused of leaking a secret memo on the Iraq war in which U.S. President George W. Bush is reported to have threatened to bomb Arabic TV station Al Jazeera. Prosecutors told the court the Britons, a civil servant and a political researcher, leaked the memo detailing "highly sensitive" talks between Bush and British Prime Minister Tony Blair at the White House on April 16, 2004, because they opposed the Iraq war. British newspaper the Daily Mirror reported in November 2005 that the memo quoted Bush as saying he wanted to bomb Al Jazeera, the Qatar-based satellite broadcaster whose coverage of Iraq's insurgency had angered U.S. officials. The Mirror quoted an unnamed government official as suggesting Bush's threat was a joke, but cited another unidentified source as saying Bush was serious. It said Blair had talked Bush out of the idea. The White House has described the Mirror report as "outlandish" and Blair's spokesman last year denied allegations about the contents of the memo. In court on Wednesday, prosecutors said the four-page document, which was written by Blair's private secretary for foreign affairs, was distributed to a small group of senior staff, including the British ambassador to the United Nations and top officials at the intelligence agency MI6. It was also sent to the government's secure communications centre, where prosecutors say civil servant David Keogh, 50, made a copy of it and later shared it with 44-year-old Leo O'Connor, a researcher for a Labour member of parliament. Keogh is charged under Britain's Official Secrets Act with two counts of "damaging disclosure" for leaking the memo and O'Connor with one count. Both have pleaded not guilty. "This is a very sensitive case that concerns issues, potentially, of national security," the judge, Justice Aikens, told the jury. The trial is expected to last about two weeks. Prosecutor David Perry said that Keogh and O'Connor, who both live in Northampton, central England, knew each other through a political "dining club". He accused Keogh of passing the copy of the memo to O'Connor at some point between April 15, 2004, and May 29, 2004, the day it was found in the files of Tony Clarke, an MP for Northampton for whom O'Connor worked as a researcher. Clarke, a member of Blair's Labour party, voted against the government's decision to go to war in Iraq. After he discovered the copy of the document in his papers, Clarke handed it to investigators, the court heard. Perry said scientists had found the copy that ended up in Clarke's file bore close resemblance to other copies of the memo distributed by the communications centre where Keogh, a telecommunications and cipher specialist, worked. Witnesses to be called in the trial include Sir Nigel Sheinwald, now Blair's chief foreign policy advisor and in line to be the next ambassador to Washington. The trial continues.
