Pol Capt Atcha Yatiwat of the Kamala Police said that officers at Kamala Police Station were first notified of the accident, along the Kamala-Patong Road, at about 4am.
That was after a passing motorist reported the accident to officers at a police box closest to the scene of the accident at about 3am.
By the time police arrived at the scene, the two people who were travelling on the motorbike had already been rushed to Patong Hospital.
At the scene, officers found a Honda PCX motorcycle in a drainage ditch by the side of the road, and a blue helmet that had been broken by the force of the impact.
Police identified the driver as a 41-year-old Kuwaiti man*, who remains at Patong Hospital. A report of the accident did not detail the extent of his injuries.
His passenger was identified as a 38-year-old Kuwaiti woman. The woman had died from her injuries, police confirmed.
At Patong Hospital, the Kuwaiti man told police that he was riding from Patong towards Kamala at about 12:30am when the accident happened.
However, the couple were not discovered until a passer-by noticed the motorbike beside the road at about 3am.
Police investigating the accident noted that the road surface was dry and there were no signs of emergency braking.
The path downhill is curved, and the barrier on the side of the road was damaged. There were street lights along the road where the accident happened, but the brightness was quite low at the curves, police reported.
Police believe the Kuwaiti man was not familiar with the road and lost control of the motorbike on a curve.
Police reported that he was found with marijuana his shoulder bag. Doctors at Patong Hospital are to test alcohol and drugs, police noted in their report.
Police are to coordinate with embassy officials so the respective families can be informed, said the report.
According to national road safety organisation ThaiRSC, 14 people have died and 1,604 people have been injured in road accidents in Phuket since Jan 1.
* The Phuket News is withholding the names of the Kuwaiti man and the woman until it has been confirmed that their respective next of kin have been notified.