The Polisario Front movement seeking independence for the disputed Western Sahara is accusing Morocco of violating a 1991 cease-fire agreement by sending troops and equipment into the territory.

Morocco said Tuesday it was trying to dismantle "smuggling rings and illegal trade."

U.N. deputy spokesman Farhan Haq says the U.N. mission in Western Sahara is contacting the Polisario Front and Morocco about the alleged violations to determine the facts.

He says the U.N. mission, known as MINURSO, "will deploy its capabilities if it is so required as per its mandate."

Morocco annexed Western Sahara, a former Spanish colony, in 1975 and fought the Polisario Front. The U.N. brokered a cease-fire in 1991 and established MINURSO to monitor it and help prepare a referendum on the territory's future, which has never taken place.