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.

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 in a week on Tuesday to tackle the issue.

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.

Rojas said many victims did not file a report, either out of fear of because of their “current situation in Ceuta”.

The Spanish Society of Epidemiology has warned that violence against women “cannot be considered an isolated event”.

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.

The Spanish government is facing bitter criticism from its opponents for its handling of the crisis. The hard-right Vox party said Sánchez had not “lost control of Ceuta – he has handed it over”.

Arantxa Campos, president of the Ceuta Employers’ Confederation, told the BBC: “We can’t do anything unless these people leave.

“We don’t have a plan from the government. We don’t have anything. We don’t even know when they’re going to finish screening everyone.”

The prime minister said on Monday that King Felipe VI would visit Ceuta “as soon as conditions allow”, seen as an attempt to assert Spanish authority over the exclave.

Morocco has a long-standing claim over Ceuta and its fellow autonomous city of Melilla. The last time a Spanish head of state visited the territories in 2007, Rabat pulled its ambassador from Madrid, and another royal visit may cause further diplomatic tensions.

In an interview with Spanish radio channel Cadena Ser, Sánchez made a point of saying the king had not visited Ceuta for 20 years – even though Felipe has only been on the throne for 12 years and it was Juan Carlos who visited in 2007.

He also asserted he was the only prime minister to have made an official visit to Ceuta while in office, having travelled there on 31 July as the crisis took hold.

Some Spanish commentators noted that his remarks appeared to criticise the king, whom he then met later in the day.

Unlike his political opponents, Sánchez has been careful to avoid blaming Morocco for stoking the surge of migrants. He said on Monday that no intelligence reports pointed to “any involvement in one way or another” from the Moroccan authorities.

Instead he focused on disinformation on social media “associated with both Russia and Israel and an international far-right movement that always uses migration, not only to attack Spain but also Europe”, although he appeared to indicate they had stoked the crisis after 31 July.

He told Cadena Ser it did not mean “it must come from a state actor”.

Russia and Israel have both denied any involvement. Israeli Foreign Minister Gideon Sa’ar accused the Spanish prime minister of “a blatant lie” and Russia’s foreign ministry spokeswoman demanded proof to support Sánchez’s allegations.

A large number of social media posts appeared in August portraying the border fence between Morocco and Ceuta as safe and easy, even though at least 100 people died while trying to swim around the border fence, according to figures from the mayor.

Spanish fact-checking website Maldita said before 30 July, when the influx began, messages circulated on Moroccan social media encouraging people to attempt the crossing, after a June ruling by Spain’s Supreme Court.

The opposition People’s Party (PP) has criticised Sánchez for “exonerating” Morocco and pointing the finger in other directions. Borja Sémper, a spokesperson for the party, said tens of thousands of people could not have moved towards the Ceuta border without Morocco’s knowledge.

Morocco has denied orchestrating or being involved in the mass crossing.