
The accident took place 100m off a privately-run pier in Phuket, after the speed boat carrying Russian tourists to an nearby island crashed into an incoming vessel.
“The cause of accident was speeding by both the drivers,” a Phuket government official said, requesting anonymity.
The brother and sister died in the crash, while “21 other Russians were injured, two critically” he added.
Thailand’s tourist industry has been hard hit by a combination of the sharp slump in Chinese visitors since the coronavirus outbreak and the strong Thai baht.
Accidents at popular resorts — mainly car, motorbike and boat crashes — are common in a kingdom with lax enforcement of safety rules.