Two men have allegedly mugged an American tourist and stolen $US40,000 ($A52,812) while he was walking in the Cairns botanic gardens in far north Queensland.

The 56-year-old man was carrying the US currency in his backpack when the men, who were on pushbikes, allegedly pushed him to the ground and ripped the bag from his shoulders last Wednesday.

The Cairns Post reported that the victim, John Markewicz, had travelled to Australia to buy a boat and sail it home.

Mr Markewicz gave chase and later found the backpack, but the cash, his passport and phone were missing, the newspaper said.

Police have urged currency exchange bureaus to be on the lookout for any suspicious transactions.

AAP

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