An 11-year-old boy has faced court over a two-day spree of alleged rapes and sex assaults in Perth's southern suburbs.

In Perth's Children's court today it was claimed that between March 9 and 10, the child raped two women and molested three others, including a woman aged 67.

The boy was the youngest of four boys charged with sexual offences against six women in total, who were aged between 16 and 67.

The boy, who was out on bail, had his bail conditions tightened after the state prosecutor successfully argued he was one of the worst offenders of the group.

In court today he appeared small and nervous sitting next to the older boys, while his mother sat at the back of the room with tears in her eyes.