Divers found McClean's corpse in the mud of a lagoon in the coastal village of Panama, 360 kilometres (225 miles) east of the capital Colombo by road, a police spokesman said.
"There were six or seven wounds on his right leg," a police official told AFP by telephone. "The body was stuck in mud at about the same place where he was seen last by some others who were with him."
A crocodile is believed to have dragged McClean away yesterday afternoon, the officer said, but a post-mortem examination later today would formally establish the cause of death.
He was on a beach and had wandered away to find a toilet when he stumbled into an area known to be infested with crocodiles.
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Other holidaymakers in the area alerted police after McClean disappeared and a search was mounted with the help of navy divers.
Crocodile attacks are rare in Sri Lanka. However, earlier this month, wildlife authorities reported that a crocodile had seriously injured a wild elephant in the south of the island.
During monsoon floods in May, authorities warned people in inundated areas to beware of stray crocodiles.