Rudd (right) made his comments following Williams' TV appearance
Few are laughing in Australia following Robin Williams' joke that its people are "basically English rednecks".
His remarks prompted Australian PM Kevin Rudd to suggest he should "spend a little time in Alabama" before commenting on people being rednecks.
That in turn offended the governor of Alabama, who said Mr Rudd should know that people in the southern state were "decent, hard-working creative people".
Williams also joked that Mr Rudd had heckled him during a recent concert.
"You go into a club and get heckled in Australia, it's kind of mandatory - 'get on with it'!
"And that was just the prime minister," the comedian said.
Speaking on The Late Show with David Letterman, Williams, 58, said Australia was an "unusual country", adding: "If [Charles] Darwin had landed in Australia, he'd have gone, 'I'm wrong - I don't know what I was thinking'."
Mr Riley said Alabamans were decent and hard-working people
Commentators have since pointed out that the famous naturalist spent two months in Australia in 1836.
Williams, recently seen in critically-slated comedy Old Dogs, went on to joke about Australian-rules football, which he likened to "rugby with a thong".
In an Australian radio interview on Wednesday, Mr Rudd hit back at Williams' comments.
"I think Robin Williams should go and spend a bit of time in Alabama before he frames comments about anyone being particularly redneck," he said.
But in doing so, the chain of offence moved on to Alabama, with Gov Bob Riley issuing a statement saying: "I'm not sure if Prime Minister Rudd has ever been to Alabama."
"If he has, he would know that Alabamians are decent, hard working, creative people."
Oscar-winning Williams, who performed in Australia last year as part of an international tour, underwent heart surgery last March to replace an aortic valve.