Police say two Russian tourists were badly injured at a Thailand beach resort when a speedboat's propeller severed one man's leg and cut deep gashes in the other man's leg.

The men, believed to be in their 30s, were struck while they were diving off Phi Phi island in Krabi province Wednesday.

Police Lt. Col. Jetsada Janpum said the operator of the speedboat had been detained for questioning.

Last month, a French woman died from being struck in the head by a boat while snorkeling in Krabi. At least three other foreign tourists have died so far this year in swimming-related accidents in southern Thailand.

Thailand had 29 million foreign visitors last year, and accidents involving tourists are not uncommon.