Spain has more than doubled the strength of security forces at its North African enclave of Melilla, after about 500 people stormed its fences in the biggest border rush for years.

Madrid sent 100 more police on Tuesday and Wednesday, raising the total to 150, a source at the Interior Ministry said, and will reinforce the rapid response unit with 20 more personnel, bringing the total to 80.

Immigrants from all over Africa regularly dare the razor-wire fences of Spanish enclaves Ceuta and Melilla, which are surrounded by Moroccan territory and sea. The numbers have multiplied as increased naval patrols discourage attempts to get to Europe by boat.

Some 1,074 people breached the 12-kilometre-long fences around Melilla in the whole of 2013, according to the source, and more than 1,600 have done so since the beginning of 2014.

Once in Melilla or Ceuta, the immigrants are fed and given clothes and beds in special centres.

Many end up in continental Spain and either stay there or travel elsewhere in Europe.

Young men gathered at the centre in Melilla said on Wednesday they were happy to have come down from the mountains surrounding the enclave, where many had spent months living rough waiting for a chance to rush the border.

“We’ve made it! We’ve passed into Europe,” said one of a group of men from countries including Guinea, Mali, the Ivory Coast and Togo.

The internment centre where immigrants await processing has been overwhelmed, prompting the army to put up tents around it.

There are now around 1,800 people housed in a facility with an official capacity of 480.

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 died drowning and the shots could have caused panic among the migrants, according to Cecilia Malmström, the European Commissioner for Home Affairs.

Spain has denied this. Secretary of State for Security Francisco Martinez said in Parliament on Wednesday the migrants had not been targeted by the shots and they had not provoked any observable panic among them.

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