THIS is the shocking moment a female backpacker is smashed over the head with a bottle and drenched in blood at a Thai island party.

Two men became infuriated with the woman because her friend was sitting at the entrance of a 24-hour grocery shop in Koh Phangan, Thailand.

Onlookers captured the moment one man smashes a bottle of beer over a reveller's head at around 2.20am on Monday.

The shopkeeper said the dispute started after the men asked the woman to move because she was blocking the entrance to his store.

Phattalung Phatthana said: ''The men tell the woman not to sit in front of the shop because other tourists can't walk by.

"The woman then become angry and a fight starts.''

Another witness said she had gone to buy medicine at the store near the middle of the beach where the full moon when she found the Thai men arguing with the women.

The young woman, who recorded the clip, added: ''The man took a bottle and hit the woman on the head.

"The man is angry at me because he said I made them look bad by recording it.''

Police in Koh Phangan said they were aware of the video but had not yet received a complaint from the woman hit by the bottle.

Koh Phangan police superintendent Pol Col Sathit Kongnian said: ''Officers are looking at the video and we will investigate this by speaking to the people involved.''