At least 2,700 migrants, some 1,000 of them minors, reached Spain's North African enclave of Ceuta on Monday, Spanish officials said, a record in a single day.
A spokesman for the Spanish government delegation in Ceuta said the numbers arriving Monday were unprecedented, adding that the migrants had reached the enclave by swimming or walking at low tide from beaches in neighbouring Morocco.
None of the migrants have been hospitalised and "they are doing well", he added.
During the morning, the delegation put the number at 100 arrivals, saying they were mostly young men but also included children and some women who had used inflatable swimming rings and rubber dinghies.
Others were able to almost walk there when the tide went out, the spokesman told AFP, with the numbers climbing rapidly throughout the day. The influx appeared to have stopped by 1800 GMT, he said.
After being checked by the Red Cross, the migrants were taken to a migrant reception centre, with authorities set to meet to discuss how to handle the situation given the record arrivals.
During the last weekend of April, around 100 migrants swam to Ceuta in groups of 20 to 30. Most were deported back to Morocco.
Ceuta, together with Melilla -- Spain's other North African enclave -- have the European Union's only land borders with Africa, making them popular entry points for migrants seeking a better life in Europe.
Migrants try to reach the enclaves either by swimming along the coast or climbing the tall border fences that separate them from Morocco.
Figures published by Spain's interior ministry show that between January 1 and May 15, 475 migrants reached Ceuta by land or sea, more than double the 203 that arrived in the same period last year.
The wave of arrivals comes at a point of diplomatic tension between Madrid and Rabat after it emerged that Polisario Front leader Brahim Ghali arrived in northern Spain in mid-April and is being treated in hospital for Covid-19.
The Polisario Front has long fought for the independence of Western Sahara from Morocco, and analysts have warned the spat could threaten bilateral cooperation between Madrid and Rabat in the fight against illegal immigration.