Movement curbs affect cities of Tangier, Tetouan, Fez, Meknes, Casablanca, Berrechid, Settat and Marrakesh.
The pro-independence Polisario Front declared a three-decade-old ceasefire in disputed Western Sahara was over after Morocco launched an operation to reopen the road to neighbouring Mauritania.
Morocco said its troops have launched an operation in a no man’s land on the southern border of Western Sahara to end “provocations” by the Polisario Front.
Rabat on Friday said its troops would “put a stop to the blockade” of trucks travelling between Moroccan-controlled areas of the disputed territory and neighbouring Mauritania, and “restore free circulation of civilian and commercial traffic”.
The Polisario Front said on Friday that Morocco had broken their ceasefire and “ignited war”, but Rabat denied there had been any armed clashes between the sides and said the three-decade truce remained in place.
The group on Monday had warned that it would regard a three-decade-old ceasefire with Morocco as over if Rabat moved troops or civilians into the buffer zone on the Mauritanian border.
It warned that “the entry of any Moroccan military, security or civil entity” into the Guerguerat buffer zone “will be considered as a flagrant aggression to which the Sahrawi side will respond vigorously in self-defence and to defend its national sovereignty”.
“This will also mean the end of the ceasefire and the beginning of a new war across the region,” the Polisario Front said.
Guerguerat is located on the southern coast of the disputed Western Sahara, along the road leading to Mauritania, some 380km (235 miles) north of Nouakchott, a buffer zone patrolled by a United Nations’ peacekeeping force.
“The Sahrawi government also holds the United Nations and the Security Council in particular responsible for the safety and security of Sahrawi civilians,” the Polisario statement added.
Last week, around 200 Moroccan truck drivers appealed to Moroccan and Mauritanian authorities for help, saying they were stranded on the Mauritanian side of the border near Guerguerat.
In a statement carried by the Mauritanian news agency Alwiam, the produce truck drivers said they were returning from Mauritania and sub-Saharan Africa but “militias affiliated with separatists” had stopped them from crossing.
In recent weeks, Moroccan media outlets said Sahrawi separatists had set up roadblocks and stopped passage across the border. Al Jazeera could not independently verify the reports.
The UN also cited isolated incidents at Guerguerat in a recent report.
Riccardo Fabiani of the International Crisis Group told Al Jazeera from Lisbon that the latest flare up could be a “potential breaking point” that could have major repercussions.
“It is very important to understand in the the next hours and days what the Polisario group is willing to do – if they are willing to escalate even further, their and actions and initiatives, and how foreign actors can step in and help mediate,” he added.
Fabiani said the United Nations had been “quiet negligent” towards this issue, citing the lack of a UN special envoy for the past few months “to try and mediate between the two sides”.
UN chief Antonio Guterres expressed “grave concern” on Friday over the situation in Western Sahara.
“In recent days, the United Nations, including the Secretary-General, has been involved in multiple initiatives to avoid an escalation of the situation in the Buffer Strip in the Guerguerat area and to warn against violations of the ceasefire and the serious consequences of any changes to the status quo,” said spokesman Stephane Dujarric.
“The Secretary-General regrets that these efforts have proved unsuccessful and expresses grave concern regarding the possible consequences of the latest developments,” he added.
Algeria on Friday “strongly” condemned “serious violations” of the ceasefire in Western Sahara, calling for the “immediate cessation” of military operations.
“Algeria calls on both parties, the Kingdom of Morocco and the Polisario Front, to show a sense of responsibility and restraint,” the foreign ministry of Algeria, which backs the Polisario pro-independence movement, said in a statement.
Western Sahara, a vast swath of desert on Africa’s Atlantic coast, is a disputed former Spanish colony.
Rabat controls 80 percent of the territory, including its phosphate deposits and its fishing waters.
Morocco, which maintains that Western Sahara is an integral part of the kingdom, has offered autonomy but insists it will retain sovereignty.
The Algeria-backed Polisario Front, which fought a war for independence from 1975 to 1991, demands a referendum on self-determination.
The two sides signed a ceasefire in September 1991 under the aegis of the UN after 16 years of war, but the planned referendum has been repeatedly postponed due to a dispute between Rabat and the Polisario over the composition of the electorate and the status of the territory.
Negotiations on Western Sahara involving Morocco, the Polisario, Algeria and Mauritania have remained suspended for several months.