A steady stream of migrants tried to swim to the Spanish enclave of Ceuta this morning, after a record influx of arrivals sent diplomatic tensions soaring between Spain and Morocco.
A European commissioner vowed that the continent would not be "intimidated" after around 8,000 people rushed into Ceuta since Monday.
Spanish Prime Minister Pedro Sanchez vowed to "restore order" after the unprecedented surge, and said today that some 4,800 migrants had been sent back.
The influx comes against the backdrop of soaring tensions with Morocco over the Spanish government's
decision to provide medical treatment for the leader of the Western Sahara independence movement, Polisario Front, who has been seriously ill with Covid-19.
It has revived the thorny issue of migration into the EU, with the Vice President of the European Commission, Margaritis Schinas, saying the continent "won't be intimidated by anyone."
Speaking on Spanish radio, he said there have been "a few attempts by third countries... over the past 15 months" to leverage the migrant issue.
In a veiled reference to Morocco's government, Mr Schinas said that Europe would "not be a victim of these tactics".
"Ceuta is Europe, this border is a European border and what happens there is not a problem for Madrid, but a problem for all" Europeans, he said.
"No one can intimidate or blackmail the European Union," he said. "We cannot tolerate this."
On the ground, people continued to gather on the Morocco border with Spain.
As the sun rose, a handful of people were swimming to reach the Spanish side, their slow progress carefully watched by dozens of soldiers deployed along the beach with riot shields and batons, according to an AFP correspondent on the scene.
It was not clear how many managed to cross, but those who made it to shore were immediately picked up by soldiers and escorted to where medics were offering help, although few appeared to need it.
No-one appeared to be hurt, but some seemed exhausted by the effort.
They were then brought back to the border fence where they were sent home.
Although the distance between African territory and Europe technically involves a swim of barely 200 metres, many tried to push beyond the nearest beach to avoid the waiting troops.
"Viva Espana" yelled one repeatedly, before starting to call for help in increasingly panicked tones to a nearby rescue boat.
Through the border fence, large crowds of hundreds of people were massed on the neighbouring Moroccan beach.
Sharp cracks rang out as tear gas canisters arched through the air leaving a trail of smoke as they landed on the beach.
By the border post on the Spanish side, a group of around 50 Moroccan youngsters, many of them teenagers, hung around aimlessly, waiting to be sent home.
Analysts said it was clear Morocco had turned a blind eye to the human tide surging into Ceuta to put diplomatic pressure on Spain to recognise its sovereignty over Western Sahara.
Most of the migrants had crossed into Ceuta largely unimpeded by Moroccan security forces on Monday, but by yesterday morning, Morocco had deployed reinforcements at the Fnideq border crossing who fired tear gas to disperse those trying to slip across.
The migrants reached Ceuta by swimming or by walking at low tide from Moroccan beaches a few kilometres to the south, some using inflatable swimming rings and rubber dinghies.
One man drowned en route, Spanish officials said.
The crisis comes after Spain allowed Polisario Front leader Brahim Ghali to fly to northern Spain in mid-April to be treated for Covid-19, angering Morocco.
The Polisario Front has fought for the independence of Western Sahara, a former Spanish colony that is mainly under Moroccan control.
The Moroccan authorities have long wanted Spain to acknowledge their authority over Western Sahara, as Washington did in December under former president Donald Trump, and were using the Ghali spat to put pressure on Madrid.