Hundreds of people forced their way though razor-wire barriers into Spain's North African enclave of Melilla on Wednesday, highlighting increasing pressure on a rare land-based route into Europe for illegal migrants.
More than 1,000 stormed fences into the enclave at around 0400 GMT and about 400 had managed to breach the border, the Spanish city's mayor Juan Jose Imbroda said in a radio interview.
Immigrants from all over Africa regularly attempt to cross the fences at Melilla and a second Spanish enclave along the coast, Ceuta. Both are surrounded by Moroccan territory and the Mediterranean sea.
Spain has beefed up security there in recent months as numbers have swelled, in part in response to increased naval patrols that are discouraging attempts to get to Europe by boat.
"There were waves (of people), they were difficult to stop," Imbroda told Spanish radio. "Moroccan police collaborated quite a bit, but the pressure was great, a chunk of the exterior fence gave way."
In March about 500 people forced their way across the Melilla border, and around 2,000 have breached the 12-kilometre barriers so far this year, up from just over 1,000 for the whole of 2013.
The immigrants who got into Melilla on Wednesday were heading for the city's temporary migration centre, where they are usually fed and given clothes.
The centre is designed to take in 500 people but is already sheltering about 2,000. Some of those processed there make it across to mainland Spain while others are returned to Morocco.
Both Spain and Italy have attempted to persuade their northern European neighbours to bear a greater share of the increasing immigration burden, but talks on an EU-wide solution to the problem have made little progress.
Last October more than 360 people drowned within sight of Lampedusa, an Italian island off Tunisia that has long been a magnet for migrants, and in May a migrant boat sank in the sea between Libya and Southern Sicily, causing at least 14 deaths.
In February, the European Union asked Spain to explain why police had fired rubber bullets in warning when a group of African migrants tried to wade and swim to Ceuta. Fifteen drowned. Spain has said the migrants were not targeted by the shots.