UNITED NATIONS (Reuters) - The conflict in Mali threatens to spill over into the disputed territory of Western Sahara and the Polisario Front independence movement has warned the United Nations of the possibility of "terrorist infiltrations," the U.N. chief said in a new report.
Morocco took control of most of Western Sahara in 1975 when colonial power Spain withdrew, prompting a guerrilla war for independence that lasted until 1991 when the United Nations brokered a cease-fire and sent in a peacekeeping mission known as MINURSO.
"During meetings with MINURSO, Frente Polisario commanders have not ruled out terrorist infiltrations," U.N. Secretary-General Ban Ki-moon said in a report to the 15-nation Security Council obtained by Reuters on Monday.
"Possible armed infiltrations, gaps in regional security coordination and resource shortages for effective border controls expose military observers to risk," the report said.
France launched a military offensive in Mali in January against Islamist militants threatening the capital. That drove the insurgents out of the towns they had seized, but they have since hit back with suicide attacks and guerrilla-style raids.
Western powers are concerned that Mali's vast and lawless Saharan desert could become a launchpad for international militant attacks. Other European governments have ruled out sending combat troops but are backing a military training force.
"All governments consulted raised serious concern over the risk that the fighting in Mali could spill over into the neighboring countries and contribute to radicalizing the Western Saharan refugee camps," Ban's report said.
One government called the situation in Western Sahara a "ticking time bomb," Ban said.
France launched a military offensive in Mali in January against Islamist militants threatening the capital.
Rabat has long tried to convince Polisario, which represents the Saharawi people, to accept its plan for Western Sahara to be an autonomous part of Morocco.
Polisario instead proposes a referendum among ethnic Sahrawis that includes an option of independence, but there is no agreement between Morocco and Polisario who should participate in any referendum.
The referendum has never been held and attempts to reach a lasting deal have floundered.
No state recognizes Morocco's rule over Western Sahara but the Security Council is divided. Some non-aligned states back Polisario but veto powers France and the United States have continued to support Rabat.
The Polisario accuses Morocco of routine human rights violations in Western Sahara and has called for MINURSO to have the authority to conduct independent human rights monitoring. That is something that the Polisario have called for in previous years but Morocco, backed by France, has rejected the idea.
In his report, Ban argued in favor of some form of independent rights monitoring but offered no details on how it would be carried out in the resource-rich territory.
"Given ongoing reports of human rights violations, the need for independent, impartial, comprehensive and sustained monitoring of the human rights situations in both Western Sahara and the camps becomes ever more pressing," Ban said.
He also recommended renewing the mandate for the U.N. peacekeeping mission in Western Sahara for another year until April 30, 2014, as well as adding 15 military observers and six U.N. police officers to the force.
Western Sahara, which is slightly bigger than Britain, has under half a million people known as Sahrawis. But it is rich in phosphates - used in fertilizer - and, potentially, offshore oil and gas.
U.N. special envoy Christopher Ross has been discussing the possibility of reviving negotiations on the future of Western Sahara with countries in the region.
Reporting By Louis Charbonneau; Editing by Bill Trott