Western Sahara's pro-independence Polisario Front bombarded the Guerguerat buffer zone under Moroccan control in the far south of the desert territory in an overnight attack Rabat described as part of a "propaganda war".
"The Saharawi army launched four rockets in the direction of Guerguerat," on the border between Morocco and Mauritania, the Saharawi press agency SPS said in a statement Sunday, citing a military leader of the separatist Saharawi forces.
Morocco launched a military operation on November 13 in the buffer zone of Guerguerat, in the extreme south of the former Spanish colony, to drive out a group of Saharawi militants who were blocking a transit route to neighbouring Mauritania.
The SPS statement also reported attacks along the security wall that separates Saharawi fighters from Moroccan forces in the vast desert expanse.
A senior Moroccan official contacted by AFP in Rabat said: "There was harassing fire near the area of Guerguerat, but it did not affect the trunk road, traffic was not disrupted."
"It's been part of a cycle of harassment for more than three months," he said.
"There is a desire to create a propaganda war, a media war, on the existence of a war in the Sahara" but "the situation is normal", he said.
Western Sahara is a disputed and divided former Spanish colony, mostly under Morocco's control, where tensions with the Polisario Front have simmered since the 1970s.
In November, Morocco sent troops into a UN-patrolled buffer zone to reopen a key road leading to Mauritania.
The Polisario responded by declaring a 1991 ceasefire null and void, arguing the road had not existed when the truce was signed.
The two sides are reported to have since exchanged regular fire along the demarcation line.
The UN-backed ceasefire deal was meant to lead to a referendum on self-determination.
Morocco has offered autonomy, but maintains the territory is a sovereign part of the kingdom.
UN-led negotiations involving Morocco and the Polisario, with Algeria and Mauritania as observers, have been suspended since March 2019.
The Polisario Front, which fought a war for independence from Morocco from 1975 to 1991, said it was still willing to join UN talks on the territory's future -- but would not lay down its arms.
"In the past, we put all our trust in the international community and definitively ended our armed struggle," senior Polisario security official Sidi Ould Oukal said on Tuesday.
"We have waited 30 years. Thirty years of broken promises, prevarication and untenable waiting."
Ould Oukal insisted the group was "open to any mediation".
"But at the same time, we will keep up the armed struggle, based on past experiences," he said.
For its part, Morocco's position was reinforced last year by US recognition of its sovereignty over the entire disputed territory, breaking decades of precedent.
The move came under president Donald Trump in exchange for Rabat normalising relations with Israel.