Ceuta, on Morocco’s northern coast, is separated from mainland Spain by the Strait of Gibraltar and has long been a focal point for migrants attempting to reach Europe.
Local officials had appealed to Madrid for help after a recent rise in attempted crossings, but there were chaotic scenes on Thursday as border controls apparently broke down.
The astonishing estimation by Spanish officials suggests the number of migrants who entered into Ceuta in the last day or so could be more than half of the population of the city – which sits at around 83,600, according to the latest local figures.
Spain later deployed its armed forces to bolster security in Ceuta and at its sister city of Melilla, where between 300 to 400 crossings were also reported overnight.
Coveted by Morocco, both cities have long been a flashpoint in diplomatic relations with Spain. Madrid asserts that both territories are integral parts of Spain and have the same status as the semi-autonomous regions on its mainland.
They form the European Union’s only land borders with Africa.
