Mr Rudd said Mr Powell's admission suggested that Australia went to war based on a lie and Mr Howard should explain why Australian troops were sent to Iraq.
"If Labor win the next election, they're going to have to work with Colin Powell," Mr Downer said. "My advice to them is that I don't think Colin Powell is going to think Kevin Rudd is a great guy if Kevin Rudd is running around suggesting he's a liar. I don't think Colin Powell will warm to that.
Powell doubts evidence for war
COLIN Powell has conceded that evidence he presented to the United Nations to justify the US-led invasion of Iraq might have been wrong.
The US Secretary of State admitted that the dramatic case he made to the UN Security Council in February 2003 was based on flawed intelligence about Iraq's weapons programs.
'At the time I was preparing that presentation it was presented to me as being solid,' he said at the weekend.
'Now it appears not to be the case, that it was that solid.'
Mr Powell made the admission when talking to reporters on a flight home from a trip to Europe.
It's never been easy to take Foreign Minister Alexander Downer seriously. His recent habit of screeching anti-American at the drop of a hat (any hat, anywhere) is making it even harder.