This is the bizarre moment a woman stripped to her underwear and danced through a river after breaking up with her boyfriend.

The half-naked 21-year-old was seen on Monday morning wading through the To Lich river in Quan Hoa district, Vietnam.

She spent some 20 minutes splashing around before police arrived and coaxed her into the back of a patrol truck.

Onlookers said she was ''dancing and singing'' in the river. Huyen Nguyen, who filmed the bizarre behaviour, said: ''She walked onto a island of flowers in the middle of the river and was in her underwear.

''Right after making the video she went into the water and was dancing and singing.''

According to local media, the woman was taken to the police station where she told officers she had separated from her boyfriend a few days before.

The Quan Hoa district police chief said: ''Immediately after receiving information, the unit sent officers to the scene put her on the shore safely.

''The girl was taken to the ward police headquarters. The original cause was determined to be a psychologically abnormal girl.

''The woman said she had been having issues with her love life for the last few days. Apart from this we have not seen any more unusual signs in her character.''

Police said the woman was tested for drugs but the results were negative. She was taken to the nearby hospital for checks.