... Refugee advocates this week said women in the Nauru centre were regularly required to strip and exchange sexual favours with guards for access to the showers, prompting calls for an investigation by the opposition Labor and Greens parties. Greens senator Sarah Hanson-Young said there were also accusations children had been forced to have sex in front of guards at the centre. Immigration Minister Scott Morrison told reporters an independent investigation headed by a former integrity commissioner and working with the Nauru government had been appointed to look into the claims. ... Save the Children Australia, which provides counselling and support on the island, said ... "The truth is that cases of child self-harm on Nauru are a reality that has been well documented," the group said in a statement. "Children have taken the drastic step of sewing their lips together and refusing food and water in protest at their indefinite incarceration."