RABAT, Morocco (AP) — Clashes between police and Moroccan protesters Thursday left at least 83 injured in clouds of tear gas and running battles at an unauthorized demonstration over inequality and corruption.

Moroccans have in recent days demonstrated in Rabat and as far away as Amsterdam to show their support for the protesters who gathered Thursday in El Hoceima, a city that has become a symbol for rising public anger.

Their Hirak protest movement has become the biggest challenge to the kingdom, a key U.S. ally known for its stability, since the Arab Spring in 2011 overthrew longstanding regimes elsewhere in the region.

Moroccan activist leader Nasser Zefzafi called for a protest in El Hoceima on July 20 — the anniversary of an uprising against Spanish colonizers — before his arrest last month in a dramatic manhunt.

Authorities banned Thursday's demonstration for administrative reasons, but crowds gathered anyway.

Police ringed the city center and fired tear gas to disperse crowds, then held running battles with protesters who scattered into side streets, according to Moroccan media reports. Internet access in the city was restricted for hours.

The government said in a statement that masked protesters hurled projectiles at police. It said 11 protesters were hospitalized and 72 police officers injured.

Protesters are demanding government investment in the impoverished northern Rif region, and justice for a fish vendor crushed by a garbage compactor last year while trying to save fish that officials had confiscated.

The death unleashed protests that have simmered for months.

The government has promised development projects for the region, which has a long history of rebellion against Morocco's leaders.

The head of the Tangiers-Tetouan-El Hoceima region, Mohamed El Yaacoubi, called the protest "useless" because the protesters' demands "correspond exactly with the projects launched by His Majesty," according to La Depeche website.

Police have rounded up dozens of activists in recent months, accusing some of receiving foreign money and support for protests seen as threatening Morocco's reputation.

The arrests only enflamed public anger, as activists in other cities took to the streets in support of the Hoceima movement. Human rights activists are demanding the release of Zefzafi and the other protesters and say authorities are increasingly aggressive against demonstrations.