An American man and Thai woman drowned after allegedly ignoring a red flag weather warning to swim at a beach in Thailand.

James Edmond Newman, 44, from New York, was washed ashore, while Waranya Chanphai, 48, from Surin province, was found floating off Mai Khao Beach in Phuket amid rough weather on June 17.

Police Major Ronnapoom Permpoon of the Thachatchai Police Station said cops received a report at 7:07 am.

They arrived at the scene and found the shirtless American man wearing only black shorts, with bruises on his back believed to be caused by the impact of the waves.

The Thai woman was floating in the seawater a few feet off the shore. An initial examination found no signs of assault on her.

The bodies have been taken to the Thalang Hospital for a post-mortem examination to determine the causes of death.

Police said the pair had checked into a nearby hotel on June 16, then went to swim at the beach the following morning.

Police Major Ronnapoom said: 'It is believed that one of them was swept away by a wave, and when the other went to help, they too were struck and drowned. However, we are still investigating the exact cause of death.'

Village council leader Winai Sae-aew said hotel staff called to inform him that a foreigner had drowned in front of the hotel.

He said: 'I immediately went to the scene and alerted the rescue team and police. Residents also assisted with retrieving both of their bodies.

'They may have been guests of Mai Khao Palm Beach Resort and were swimming in the morning when there was no lifeguard present, but there was a red flag put up.

'I cannot confirm if they were husband and wife. Further confirmation is needed.'

Thailand and neighbouring countries in Southeast Asia are at the start of their annual monsoon rainy season which sees soaring temperatures followed by powerful rain storms. The rudimentary infrastructure often struggles with the deluge, leading to widespread flash floods.