The couple, who were both wearing helmets, were killed instantly, Capt Akkaraphon Siwilai of the Tha Chatchai Police.
Capt Akkaraphon said police were notified of the accident at 1:50pm.
Officers arrived at the scene, in the southbound lane of Thepkrasattri Rd near Baan Bang Duk in Mai Khao, to find the body of Rachot Saengwan, 35, who was driving the motorbike when the accident happened, on the road, and the body of his passenger, Jirawan Naulkao, 25, on the central traffic island.
Nearby was the remains of the motorbike, a Honda ADV 150, smashed into two main pieces, with other fragments scattered around.
“CCTV footage showed that Mr Rachot and Miss Jirawan were riding southbound after passing through the Phuket Check Point [at Tha Chatchai],” Capt Akkaraphon explained.
Mr Rachot was riding at speed, keeping pace with cars travelling in the right-hand lane when his bike veered towards the central reservation and struck it, he said.
“Their motorbike hit a concrete pole fitted with a traffic sign and a tree,” he added.
No other vehicles were in any way involved with the accident, Capt Akkaraphon confirmed.
“There were no other factors, no other vehicle was near them and there was nothing on the road, so all I can presume is that Mr Rachot lost control of the motorbike,” he said.
“This is what I noted in my report before informing their relatives so that they can make arrangements for the funeral ceremonies,” Capt Akkaraphon said.