Quoting leaked documents, London's Daily Telegraph reported on Saturday that a senior Foreign Office official felt the war was more of a grudge match between Bush and the former Iraqi ruler Saddam Hussein.
"Even the best survey of Iraq's weapons of mass destruction programme will not show much advance in recent years," the official said in the memo.
"Military operations need clear and compelling military objectives. For Iraq's regime change does not stack up. It sounds like a grudge match between Bush and Saddam".
Downing Street said it would not comment on the leaked documents, but added the government "firmly believes that Iraq is a better place for the removal of Saddam Hussein".
Death and destruction continue
to play havoc with Iraqi lives
The US, aided by British and other allies, invaded Iraq last year on the basis that Baghdad had banned weapons of mass destruction, although no biological or chemical weapons have been found till date.
Bush's father was president during the first Gulf War when a US-led coalition freed Kuwait in 1991, and then drove Saddam's forces back into Iraq before withdrawing.
The leaked papers also showed that officials, including the British Foreign Secretary Jack Straw, expressed concern about possible chaos in a post-Saddam Iraq.
"No one has satisfactorily answered how there can be any certainty that the replacement regime will be any better," the Telegraph quoted Straw as saying in a note to Prime Minister Tony Blair marked ''Secret and Personal''.