TIMELINE: Western Sahara, a 50-year-old dispute

(Reuters) - A third round of negotiations to settle Africa’s longest-running territorial dispute resume next week in New York when negotiators from Western Sahara and Morocco sit down for talks.

Here is a chronology of the Western Sahara dispute.

1884 - Spain colonizes Western Sahara.

1957 - Morocco raises centuries-old historical claim to Western Sahara at the United Nations.

1973 - Polisario Front is formed and establishes itself as the sole representative of the Sahrawi people.

June 1975 - Morocco’s King Hassan takes the territorial dispute to the World Court in The Hague. The court finds that some tribes had paid allegiance to Moroccan rulers, but rules that people should be allowed to settle the sovereignty issue through self-determination. Spain will organize a referendum.

-- November - King Hassan launches the Green March with 350,000 unarmed Moroccans crossing into the territory. Spain agrees to transfer administration of the territory to Morocco and Mauritania.

-- December - Morocco sends in forces to occupy the territory.

1976 - As Spanish troops withdraw, Polisario guerrillas backed by Algeria and Libya proclaim the Saharan Arab Democratic Republic (SADR) with a government-in-exile based in Algeria.

1979 - Mauritania signs a peace deal with Polisario and renounces its claim to Western Sahara.

1980 - Morocco annexes Mauritania’s share of the territory.

1984 - SADR is admitted as a member state of the Organisation of African Unity (OAU). Morocco leaves the OAU.

1991 - U.N. brokers ceasefire, ending the guerrilla war between Polisario and Moroccan forces. The U.N. Mission for the Referendum in Western Sahara is established to oversee the ceasefire. A referendum is set for January 1992 but is postponed because of a dispute over who is eligible to vote.

2001 - Former U.S. Secretary of State James Baker proposes autonomy for Saharawis under Moroccan sovereignty, a referendum after a four-year transition period, voting rights for Moroccan settlers resident in Western Sahara for over a year. Polisario and Algeria reject the proposal.

2003 - U.N. proposes Western Sahara become a semi-autonomous region of Morocco for a transition period of up to five years, to be followed by a referendum on whether the territory should become independent, semi-autonomous or integrated with Morocco. Polisario endorses the plan but Morocco rejects it, saying it will never give up sovereignty.

October 2006 - Morocco calls a U.N. report critical of its human rights record in Western Sahara biased in favor of the Polisario Front.

December 2006 - The Moroccan advisory council proposes autonomy, burying the prospect of independence.

-- Polisario has already dismissed autonomy and the council’s draft proposal.

April 10, 2007 - Polisario says it proposes a “flexible” peace plan at the United Nations. Morocco unveils its plan the next day.

Aug 11 - Two days of U.N.-sponsored talks end with no breakthrough but agreement to meet again.

Dec 12 - Rabat urges the U.N. to stop Polisario leaders from holding a congress at which they will propose preparing to resume war with Morocco.

Dec 21 - Polisario says war may break out again if U.N.-sponsored talks fail.

Writing by David Cutler, London Editorial Reference Unit