He's lampooned the French, been beastly to the Germans, and poked gentle fun at the Luxembourgers. Now Bill Bryson is tackling the most anti-American nation on earth. Not Iran, Syria, nor even North Korea, but Canada.

The Des Moines-born travel writer is no subscriber to George Bush's theories on rogue states - he calls his president an imbecile.

He has been wondering aloud whether to turn his legendary acerbic stare on the Middle East, and Syria in particular, a country he finds fascinating.

But Canada, so often overlooked as too dull by travellers, seems to have got the vote. "You have such an interesting story there," he told an audience of 1,000 fans at the Guardian Hay Festival. "It is also easier - I'm chicken.

"I'm not that comfortable about writing about the third world," hesaid. "I find it hard to make jokes when people are sleeping under bridges and don't have enough to eat."

In a career which he readily admits is based on "travelling the world and making fun of people", Bryson has been curiously nice about the United States' northern neighbour.

"When I do a reading in Canada I get bigger laughs than in the US. They get it right away. With Americans you have to smile a lot to let them know it's a joke. It's a different culture."

Nevertheless, publishers have yet to be convinced that an interesting book can be written about the land of moose and Mounties. "You mention Canada, and their faces go ashen," he said.

Bryson, who is about to return from America to live near Norwich, said he was inspired to write his new book about science, A Short History of Nearly Everything, because his son's chemistry books were so boring.