MADRID - Moroccan police have arrested 11 Spanish activists in Western Sahara who were demonstrating for independence for the disputed territory, the Spanish Foreign Ministry said Sunday. The detainees were later released but are waiting to return to Spain at a Spanish diplomatic residence called "Casa de Espana" in Aaiun, the capital city of the former Spanish colony. Western Sahara, a disputed territory slightly bigger than Britain rich in phosphates and potentially offshore oil, is the scene of Africa's longest-running territorial dispute. Morocco annexed Western Sahara as the Spanish left in 1975 and is now offering it autonomy. But the Polisario Front, which fought a guerrilla war until 1991, demands a referendum with independence as an option. The arrests come days after Spain sought to ease tensions with Morocco, saying sporadic blockades by anti-Spanish demonstrators at the gates of its Melilla enclave on the north African coast had served to bolster police cooperation between the two countries. The 11 Spanish activists, waving flags, were the only people demonstrating when they were immediately arrested in Aaiun. They said they suffered physical abuse at the hands of Moroccan authorities and published pictures of bruised skin and black eyes on a website in favor of an independent Western Sahara. "We are at the Casa de Espana not of our own free will, but because our safety feels less at risk here," one of the activists from Saharacciones, Alexis Dorta, told Spanish national radio. Spain's Foreign Ministry said in a statement that government representatives would accompany the activists back to Spain by boat Sunday night.