A piano teacher has been arrested for alleged indecent assault on a 10-year-old girl pupil at his music school in Bangkok.

Police arrested Veeranan Lerdpanyaroj, 43, alias “Khru Ju”, at 77 Musical, a music school on Soi Sukhumvit 77 in Phra Khanong Nua.

Seized from his school were a mobile phone, an iPad and a notebook computer with more than 1,000 child pornography videos, condoms, birth-control pills and a tube of lubricant gel. The condoms, pills and gel were found in a classroom, according to police.

During the raid on Tuesday, the accused teacher was found lying naked and masturbating in his bedroom inside the school, according to the arresting team.

Police said the mother of a 10-year-old girl told police that her daughter enrolled for piano lessons at 77 Musical.

She was waiting to pick up her daughter, when the girl ran crying from the music school. Her daughter alleged that the music teacher touched her private parts. She immediately took her child home and told police.

According to the victim's mother, her daughter said the accused teacher had first pressed his crotch up against her back when she was playing piano in January this year. He continued to do this every time she took a lesson.

In February, he allegedly forced her to lay down on the piano chair, removed her pants and performed an indecent act. The girl did not tell her mother at the time because she did not understand what the teacher was doing.

On May 17, he allegedly placed her hand inside his trousers. The girl was frightened and immediately pulled her hand away, according to the mother, and ran crying from the school.

Mr Veeranan denied the charge of indecent assault, but admitted owning child pornography, according to poliice.