An "unprecedented" pro-independence demonstration in several decades took place on Saturday in Laâyoune, the largest city in Western Sahara, a former Spanish colony controlled by Morocco, several Moroccan media reported on Monday.

According to the authorities in Laâyoune, some 500 people marched peacefully at the end of the day, without intervention from law enforcement. Violence, however, broke out in the evening after the procession dispersed, and at least 21 police officers were injured, according to the same sources. One of them is in serious condition and has been transported to Rabat.

The clashes also left an undetermined number of injured among the demonstrators, claimed a local official of the Moroccan Association for Human Rights (AMDH, independent), Hamoud Iguilid.

The demonstration, which took place while North American media journalists were in Laâyoune, gathered more than 2,000 people, said the regional coordinator of the National Human Rights Council (CNDH, official), Mohamed Salem Charkaoui, cited by the Lakome website.

"An unprecedented mobilisation of the enemies of territorial integrity," estimated the daily Aujourd'hui Le Maroc on Monday, citing "consistent sources".

"The largest demonstration in the history of Laâyoune for separation," also headlined Akhbar al-Youm, noting the presence in the procession of Polisario (pro-independence) flags but also American flags.

Another gathering took place on Sunday in Smara, about 200 km east of Laâyoune, and 17 members of the security forces were injured "to varying degrees," the city's authorities announced on Monday, cited by the MAP agency.

People "erected barricades in an attempt to occupy the public highway and hinder traffic, creating a situation of chaos," the statement added, without detailing the precise motivations of the demonstrators.

Several pro-independence gatherings have taken place since the renewal, at the end of April, of the UN mission in the Sahara (Minurso), whose mandate was ultimately not extended to human rights, as Washington had at one time expressed the wish. Morocco had strongly opposed the project.

On April 27, a demonstration in which about a hundred people participated, according to the AFP correspondent, had degenerated into violence in Laâyoune, leaving about forty injured: 30 demonstrators according to the NGO Amnesty International, whose team was on site, and eight police officers according to the authorities.

Speaking on Monday before the deputies, the Minister of the Interior Mohand Laenser stated that the toll of the "latest events" in the region amounted to "150 injured" among the security forces, some of whom were seriously injured.

The demonstrations were "meticulously prepared, the main objective being to provoke the security forces and push them to intervene to exploit the images in the media," he argued, accusing "foreign circles" of having financed such a "plan".