Madrid  - Spain on Tuesday lent cautious support to Morocco's proposal of an autonomy to Western Sahara in the search of a solution to the three-decade conflict pitting Morocco and the Saharawi independence movement Polisario Front.

The proposal to grant the region autonomy instead of independence was a "positive contribution" to negotiations towards a "fair, lasting and mutually acceptable peaceful solution that respects the principle of self-determination," Spain and Morocco said in a joint declaration issued after a summit in Madrid.

Morocco and Polisario needed to be "flexible" in the negotiations supervised by the United Nations, Spanish Prime Minister Jose Luis Rodriguez Zapatero advised, proposing Spain's semi-autonomous regions as a possible model for Morocco to follow.

Polisario rejects the autonomy solution and insists on a referendum on independence, an option proposed by a 1991 UN plan which has not been put into practice.

At a joint press conference, Zapatero and his Moroccan counterpart Abbas el-Fassi described bilateral relations as good despite the brief crisis opened by the visit of Spain's King Juan Carlos in 2007 to the Spanish enclaves of Ceuta and Melilla, which are claimed by Morocco.

The two countries pledged to continue fighting illegal immigration from Morocco to Spain, and signed an economic agreement worth 520 million euros (712 million dollars) to boost Spanish investments in Morocco. (dpa)