Some 72,000 migrants breached the border in an unprecedented and deadly rush on July 30-31, with 70,000 having since returned to Morocco, according to Spanish government figures.

But the thousands who remain -- including hundreds of unaccompanied children who cannot be summarily deported -- struggle to access food, water, shelter and sanitation while the tiny enclave's resources are overwhelmed.

READ ALSO: Migrant children sleeping rough in Spain's Ceuta at risk of abuse

Their future has sparked a political battle between Spain's leftist central government and regions governed by the main conservative Popular Party (PP) and far-right Vox, which resist taking in unaccompanied children under existing legal provisions.

"A space that acts as an internment centre for foreigners must be set up, where these people can be held and remain confined," Ceuta's PP leader Juan Jesús Vivas told reporters.

He said the measure "must be achieved urgently" so that the migrants "are not in our streets and that expulsion proceedings can be handled with greater speed and ease".

Vivas called the situation "unsustainable", estimating that between 8,000 and 11,000 migrants were left in Ceuta, well above the government's figure of around 2,500.

Thousands of residents of the territory of 84,000 inhabitants gathered to protest on Sunday at the handling of a crisis that they say has left Ceuta insecure and abandoned.

The Spanish government minister responsible for relations with the regions, Ángel Víctor Torres, assured Ceuta's population that police and troop numbers had been ramped up, including 40 percent more Civil Guards.

Reuniting the children with their families was "the priority", he added, without mentioning the possibility of expulsions.