Spanish Prime Minister Pedro Sánchez has said no-one foresaw the influx of 72,000 migrants in the exclave of Ceuta, as pressure mounts over his handling of the crisis.

“It’s absurd to think that the government knew and did nothing,” Sánchez told Spain’s parliament on Thursday, hours after tens of thousands of people joined protests across the country backed by opposition parties.

Sánchez also maintained there was no evidence Morocco was behind the mass crossing and there had been “close co-ordination” between the two countries.

A Spanish police report has highlighted the “total permissiveness” of Moroccan security forces, although senior officials insist it does not point the finger at Rabat.

Although most of the migrants have been sent back to Morocco, some 5,000 remain on the streets and beaches of Ceuta, on the North African coast, including as many as 1,400 children.

There have been several reports that Spanish officials had been warned of a rise in sea arrivals over the border at Ceuta, following a Spanish court ruling that many migrants misunderstood to mean they would not be pushed back if they swam across.

Opposition People’s Party leader Alberto Núñez Feijóo accused the government of lying and a cover-up, and said the prime minister should resign.

Spain’s handling of the migrant influx angered some of its European partners, and Italy responded by imposing border restrictions on arrivals from Spain.

The large turnout for the demonstrations in Madrid and other cities on Wednesday underlined the pressure Sánchez is under domestically too.

The protests were ostensibly held to express support for the people of Ceuta, but as frequent anti-government chants have shown, they also reflected public anger at the ongoing crisis.