A disabled kindergarten pupil was sexually assaulted in a school toilet after four boys asked her to 'play a game'.

During the November 2013 incident at an Illawarra region school, two boys stood guard while two others assaulted her, stuffing toilet paper into her mouth to muffle her screams for her mother.

The attack was uncovered after the mentally and physically disabled girl came back to class after the break-time attack with her uniform inside out, according to The Daily Telegraph.

A disabled six-year-old girl was allegedly sexually assaulted in a school toilet after four boys asked her to 'play a game' (stock image)

According to police, two of the boys were aged five and nine, while the girl's mother said her daughter had identified four boys aged nine to 11.

She was supposed to be in a special needs playground - as her mother had directed school staff, she said - but was instead in the mainstream one when she was targeted.

The incident was recently revealed after the six-year-old's mother chose to sue the Department of Education over the incident.

It had devastated her daughter and family, leaving the girl 'suffering from nightmares and flashbacks all the time. The stress is insurmountable'.

A group of four boys, allegedly aged between five - 11, were said to be involved in the incident (stock image)

Shine Lawyers abuse law partner Lisa Flynn was quoted by The Daily Telegraph: 'This happened because of the school’s failure to not only properly supervise students in their care, but also respond appropriately when reports of ­assaults were made'.

The incident with the girl had been referred to the Department of Family and Community Services and police, a Department of Education spokesman said.

Police said due to the age of the boys allegedly involved, no police action would be taken.

According to the Telegraph, it's not the only alleged sexual assault at the school.

Three others were allegedly to have occurred, it was reported.