Hundreds of immigrants have tried to break through border fences around the Spanish enclave of Melilla in North Africa for a second night running.
Immigrants have used home-made ladders to scale the fences (Image: Melilla Hoy)
Some 200 succeeded in crossing, say Spanish police. Some 100 made it across the day before.
Almost 30 people, including policemen, have been injured in the mass assaults.
Melilla and nearby Ceuta are seen as stepping stones to Europe by African immigrants. Spain is doubling the height of the fences around Melilla.
Most arrive without documentation, leaving the police in Melilla to take their details and issue them with expulsion papers. Spanish newspaper El Mundo says that many of the sub-Saharan immigrants then hope to be sent to mainland Spain on the premise of being sent back to their own countries.
Almost all the migrants who make it into an enclave also claim asylum, but fewer than 10% of these applications are successful.
Police have logged 12,000 attempts to enter Melilla this year.
Many migrants are caught and many drown while attempting to make the sea crossing to Spain - either across the Mediterranean Sea or to the Canary Islands, over the Atlantic Ocean.
They cross in groups to increase their chances of getting over the double fence.
Many have already risked their lives crossing the Sahara desert in order to reach the shores of the Mediterranean. They come from across west Africa, some from as far away as the Democratic Republic of Congo, hoping to reach the European Union.
A Guardia Civil spokesman said groups had been trying to cross where the perimeter fencing remains 3m high.
It is at these points where work is being carried out to double the height.
Police have found more than 200 makeshift ladders where crossings have been attempted.
Spanish guards on the borders have responded to the attempted invasions with anti-riot methods.
The Doctors Without Borders (MSF) charity criticised what it called "the violence" used by the Spanish and Moroccan security forces.
But Spanish secretary of state for security, Antonio Camacho said that migrants were launching massive and violent assaults.
"Being an illicit action which is also, normally, accompanied by great violence on the part of the assailants, it is highly likely that - despite diligent, professional and proportionate action by police officers - unwanted situations may occur," he said.
An extra 40 police officers are being sent to Melilla.
In the past week, the Moroccan authorities have arrested more than 1,000 people planning to travel illegally to Europe.
Some 300 were Moroccan, the others from sub-Saharan Africa.