A 52-year-old Hong Kong man has drowned on the Thai resort island of Phuket while swimming with his teenage son, it emerged on Friday.

The Immigration Department confirmed receiving a request for help from the man's family, and pledged to render all necessary assistance.

According to Thai media, the duo decided to take a dip at the famous Patong beach on Wednesday when the father began drifting away.

His son notified lifesavers, who pulled the man ashore on a jet ski. He was already unconscious and was eventually pronounced dead in hospital.

The Immigration Department said it had contacted the Chinese consulate in the southern Thai province of Songkhla, with the help of the Foreign Ministry's office in Hong Kong.

A spokesman said the department will remain in close contact with all relevant parties and provide assistance according to the family's wishes.

SAR residents needing help overseas are urged to call its 24-hour hotline, (852)1868, or send a message through WhatsApp using the same number.