Moroccan authorities say six African migrants were killed as hundreds of people tried to illegally enter a Spanish enclave in North Africa.

They described the migrants as extraordinarily violent in their Thursday attempt to scale the razor-wire fence surrounding Melilla. Moroccan police arrested 290 people during the incident - the latest of almost daily attempts to enter Melilla or Ceuta, the other Spanish enclave bordering Morocco, in hope of making it to the European Union.

Five immigrants died last week trying to enter Ceuta. But Spanish officials say their troops were not responsible because they did not use live ammunition.

Spanish Prime Minister Jose Luis Rodriguez Zapatero has called on the European Union to boost economic cooperation with Africa to help stem the flow of economic immigrants from the continent.

Spain is also starting to return to Morocco any Africans who make it into the enclave.

Some information for this report provided by AFP and Reuters.