Four women allegedly present during the female genital mutilation procedures on two young girls in Sydney have been charged.

Last week, the girls' parents, a sheikh and a retired nurse were charged over the controversial procedure, also known as female circumcision.

The girls were allegedly operated on when they were aged six and seven.

Detectives attached to Strike Force Longfield have continued their investigation and are appealing for anyone with information about female genital mutilation to come forward.

They have been working in close connection with the Department of Family and Community Services since the initial four people were arrested last week.