People gather in front of the Portuguese parliament during a protest over the housing shortage, soaring rents and low wages in Lisbon. (AFP pic)LISBON: Riot police with dogs stormed protest camps in Lisbon and Porto early Sunday, charging demonstrators with batons, arresting 13 people and leaving dozens injured in the latest confrontation over Portugal's housing crisis.

Clashes quickly broke out as dozens of officers moved in on an encampment in Lisbon's Rossio Square and a smaller camp in Porto's Dom Joao I Square at around 4.30am.

Protesters shouted "smells like a dictatorship", while police said some hurled bottles and paint at officers as they tried to take down the tents.

Police said in a statement that six people were arrested in Lisbon and seven in Porto for refusing orders to disperse.