About 500 migrants stormed through the fog across the border fence from Morocco into the Spanish territory of Melilla Tuesday, the biggest such crossing in nearly a decade, officials said.
The charge, described by authorities as "violent" with migrants throwing sticks and stones, raised pressure on Madrid as it struggles with a flood of desperate Africans trying to reach Europe.
About 1,000 Africans rushed the triple-layer fence separating the Spanish city from Morocco at around 0700 GMT and half of them made it across, said the Spanish governor of Melilla, Abdelmalik El Barkani.
"It was a violent charge," he told a news conference. "Helped by the bad weather and fog, a big group of about 1,000 tried to enter and about 500 sub-Saharans succeeded."
That made it the biggest such crossing since a huge wave of migrants caused a crisis at the border in 2005.
Barkani said some of the migrants threw sticks and stones at security forces. Some migrants suffered cuts and bruises and 29 were treated by medics on the Spanish side, he said.
The Moroccan interior ministry said separately that five police officers and 28 migrants were injured on the Moroccan side.
Some were hurt by barbed wire on the top of the fences and were taken to hospital in the nearby Moroccan town of Nador, it said.
Across the Mediterranean from mainland Spain, Melilla forms one of Europe's only two land borders with Africa, along with another Spanish territory, Ceuta, to the west.
Surrounded by Moroccan territory, they offer a key entry point for Africans desperate for a better life in Europe.
- Thousands wait to cross -
Depending on treaties with the immigrants' countries of origin, some are repatriated and others are allowed to stay in Spain.
Meanwhile they wait in government-run reception centres.
The centre in Melilla is built to house 480 immigrants but was already housing 1,800 before Tuesday.
Crowds more migrants are waiting in the wild on the Moroccan side in the hope of crossing to Melilla, authorities say.
"According to our information, they are approaching" the border too, Barkani said.
Spain's Interior Minister Jorge Fernandez Diaz on March 4 estimated there were 40,000 migrants waiting to cross from Morocco into Ceuta and Melilla.
Another 40,000 were waiting to enter Morocco from Mauritania en route to the two cities, he said.
The number of Africans trying to cross into the two Spanish territories has surged over recent months. Spain's government has demanded more help from the European Union to deal with them.
On February 6 about 15 migrants drowned in Moroccan waters while trying to swim to Ceuta from a nearby beach.
Rights groups and witnesses accused Spanish security forces of firing rubber bullets at the migrants in the water.
The government admitted using rubber bullets but denied its forces had targeted the migrants directly.
It later banned civil guards policing the border from using rubber bullets to repel migrants.
More than 200 migrants stormed over the fence into Melilla on February 28, leaving 35 injured, according to officials and rights groups.
Other migrants have tried to sail to Spain's north African territories or to the mainland in flimsy vessels or enter the country hidden under car seats.