This is the baffling moment a bungling cop let a police truck roll into the sea in Thailand.

Officers drove the pickup truck to tow a jetski when it slid down a ramp and into the water in Surat Thani province on December 7 afternoon.

Footage shows officers battling to push the half-submerged truck that rolled some 15ft from the shore as onlookers gathered at the beach to watch.

The Marine Police said the pickup truck was safely retrieved on the island of Koh Samui.

They said its driver had been reversing down the slope to attach a cable to the jet ski. He engaged the handbrake, but it reportedly failed and caused the vehicle to slide into the sea.

An investigation into the incident will be conducted, authorities said.