Hundreds of pro-independence Sahrawi activists have marched in Laayoune, the Western Sahara's largest city, over the weekend in the region's biggest protest in several decades, according to Moroccan media reports.
About 500 people marched peacefully late on Saturday afternoon, but violence broke out in the evening after the protest, wounding 21 policemen, several newspapers reported on Monday.
The clashes also wounded an unknown number of activists, Hamoud Iguilid, the local representative of the Moroccan Association for Human Rights, told the AFP news agency.
Mohamed Salem Charkaoui from Morocco's official National Human Rights Council, cited by the news website Lakome, said 2,000 people took part in the Laayoune protest.
Protests took place in other Western Saharan towns on Sunday, including in Smara, where 17 members of the security forces were wounded trying to disperse protesters who had set up barricades in the streets, the official MAP news agency reported.
It gave no information on injuries sustained by the protesters, who it said tried "to occupy the street and block traffic, creating a chaotic situation".
Some of the demonstrators in Smara, around 200km from Laayoune, carried the flag of the "Sahrawi Arab Democratic Republic", other local media reported.
French-language daily Aujourd'hui Le Maroc described the Laayoune protest, which coincided with a visit by a group of foreign journalists, as "an unprecedented gathering by the enemies of [Morocco's] territorial integrity".
"The largest protest for separation in Laayoune's history," ran the headline of Arabic daily Akhbar Al-Youm, which also reported the presence of rebel Polisario Front and US flags.
Tensions have been running high in the disputed territory since the Security Council passed a resolution on April 25 which extended the UN peacekeeping mission for another year but omitted a Washington-backed proposal to broaden its mandate to include rights monitoring.
The Western Sahara is a highly sensitive issue in Morocco, which annexed the former Spanish colony in 1975 in a move never recognised internationally, and it lobbied furiously to have the US rights monitoring proposal dropped.
Dozens of demonstrators were wounded when a pro-independence protest turned violent a day after the UN vote, a representative of the UK-based rights watchdog Amnesty International in Laayoune said, adding that the police used "excessive force" to disperse the protesters.
Morocco has proposed broad autonomy under its sovereignty for the phosphate-rich territory, but this is rejected by Polisario Front rebels, who took up arms to fight for an independent state until the UN negotiated a ceasefire in 1991.
The Polisario insists on Sahrawis' right to a UN-monitored referendum on self-determination.