Some 5,000 migrants who entered Ceuta from Morocco are estimated to still be in the Spanish exclave
Spanish prosecutors say 23 sexual assaults, including nine against children, have been recorded in Ceuta since the mass influx of migrants into the Spanish exclave at the end of July.
That number meant there was almost one case every day, Ceuta's chief prosecutor Silvia Rojas said.
She told El País newspaper migrant girls were "particularly vulnerable because of their irregular status in the territory".
At least 72,000 migrants crossed from Morocco into Ceuta on 30 and 31 July and although most have returned, as many as 5,000 remain – leading to unrest in the autonomous city in North Africa and a crisis for Spanish Prime Minister Pedro Sánchez.
Between 1,400 and 1,600 of the estimated 5,000 migrants still in Ceuta are children, according to Rojas.
Among the suspected attackers are four Moroccans, three Spaniards and a Belgian, Efe news agency reports.
There have been scenes of violence in recent days as tensions flare up between migrants and local residents.
Sánchez called the second meeting of his national security council in a week on Tuesday to tackle the issue.
Rojas said the influx had led to an exponential increase in sexual assault, and many victims did not file a report, either out of fear of because of their "current situation in Ceuta".
The Spanish Society of Epidemiology said the border crisis had highlighted the difficulty in detecting and tackling violence against migrant women and girls.
One 24-year-old woman from Morocco told the BBC she had "put her life in danger" by travelling to Ceuta, and described being sexually assaulted while sleeping among a group of men and women. "I was shocked… If I had known this, I wouldn't have come."
Emergency doctor Susana Ascaso said last month her department at Ceuta University Hospital had treated several sexual assault victims, including one who was just 10 years old.
Economy Minister Carlos Cuerpo said a multi-million euro aid package had been approved by the cabinet that would help provide essential services and cover care for unaccompanied children.
The territory's conservative mayor, Juan Jesús Vivas, has called on Spaniards to take part in demonstrations across mainland Spain in support of Ceuta on Wednesday, which coincides with the city's annual holiday.
