Pro-independence rebels fighting Morocco over the disputed territory of Western Sahara said Tuesday they had killed three Moroccan soldiers in the southern Ouarkziz area the previous day. It is the first time the Polisario Front have said they inflicted losses on the Moroccan army on Moroccan soil since mid-November, but the claim could not be verified independently. Tensions rose sharply on November 13 when Morocco sent troops into a buffer zone to reopen the only road leading from Morocco to Mauritania and the rest of West Africa, after separatists had blocked it the previous month. The Polisario responded by declaring a 1991 UN-backed ceasefire null and void, arguing the road had not existed when the truce was signed and was therefore illegal. The two sides have since exchanged regular fire along the demarcation line. A statement by the Polisario's "defence ministry" said Monday's operation "against a garrison... of Moroccan forces stationed at Ouarkziz" saw it overrun then destroyed. It said Polisario fighters had seized weapons, ammunition and documents and spoke of another attack in Touizgui, towards the Algerian border, without giving details. The 1991 ceasefire deal was meant to lead to a referendum on self-determination for the Britain-sized territory, home to about one million people. Morocco has offered autonomy but maintains the territory is a sovereign part of the kingdom. The Polisario Front, which fought a war for independence from Morocco from 1975 to 1991, has said it is still willing to join UN talks on the territory's future -- but would not lay down its arms. The talks ground to a halt last March. Rabat has won the recognition of its claim to sovereignty over the entire disputed territory from numerous countries which have opened consulates in Western Sahara. agr-sof/ach/dl