Gunfire has continued along the disputed buffer zone between Morocco and the area held by the pro-independence Polisario Front in Western Sahara this week.
UN spokesman Stephane Dujarric on Tuesday said the peacekeeping mission in Western Sahara (Minurso) “continues to receive reports of shots being fired during the night at various locations”.
The Polisario said its fighters “inflicted human and material losses” in attacks along the front on Tuesday, but there was no independent confirmation, the AFP news agency reports.
Sidi Omar, the Polisario’s ambassador to the UN, said the actions of the Moroccan forces had reignited a war after 30 years of a ceasefire.
“The situation now is a state of war, both parties are engaged militarily along the Moroccan military wall and the shelling, firing continues,” he told the BBC NewsDay programme.
The flare-up started last Friday when Moroccan troops launched an operation to open a highway through the Western Sahara to Mauritania.
A ceasefire agreement between Morocco and the Polisario Front has lasted since 1991, keeping both sides behind a 2,700 km (1,700 mile) buffer zone sown with an estimated seven million landmines.