A statement issued by El Mostafa Sahel, Morocco's ambassador to the UN, after he met Ban Ki-moon, the UN chief, on Wednesday, said the Moroccan plan "aims to allow all Saharawis to democratically manage their affairs, while respecting the sovereignty and territorial integrity of the kingdom".
It said the plan grew out of "a large process of democratic consultations at the local and national levels with the participation of political parties".
It called the plan "innovative, responsible and open" and said it respected international law and UN principles.
The initiative offers "a chance for peace and promising perspectives for a better future, based on stability, security, democracy and prosperity for all the countries of the Maghreb".
On the other hand, Ahmed Boukhari, the Polisario representative to the UN, said that the Polisario plan, delivered on Tuesday, would offer the Saharawi people, who inhabit Western Sahara, Mauritania, the Canary Islands and Algeria, three choices: independence, autonomy within the Moroccan state or total integration with Morocco.
The proposal also outlines a plan for a special economic and political relationship with Morocco, if Western Sahara votes for independence.
Morocco and Mauritania split Western Sahara after its Spanish colonisers left the territory in 1975.
Full-scale war broke out the following year, and Morocco took over the whole of Western Sahara after Mauritania pulled out in 1979.
Boukhari said Morocco's proposal was "based on something that cannot be acceptable. It is based on that all of Western Sahara belongs to Morocco". That issue must be decided by elections, he said.
Before elections, Boukhari said the Polisario was ready to "engage in direct negotiations" with Morocco.
In October, the UN Security Council extended a peacekeeping mission that has monitored a ceasefire between Moroccan troops and Polisario fighters for 15 years in the sparsely populated, mineral-rich region.
However, the UN has been unable to resolve the standoff between the Algeria-backed Polisario Front and the Moroccan government.
"[The initiative offers] a chance for peace and promising perspectives for a better future".
El Mostafa Sahel, Morocco ambassador to UN
Council members have said they want to see progress on a negotiated solution to the impasse before the current mandate for the 225-member UN mission expires on April 30.
Marie Okabe, deputy spokeswoman for the UN secretary-general, said that during Ban's meeting with the Moroccan ambassador, the UN chief "expressed his appreciation as well as his hope that the parties would find a mutually acceptable solution".
Alejandro Wolff, acting US ambassador, said he had received a description of Morocco's plan and was "encouraged by the fact it encouraged a process of negotiations".
"The key focus here is going to be to see if we can get the parties to engage directly."
After meeting with a Moroccan delegation in Washington, Nicholas Burns, US undersecretary of state, called the country's plan "a serious and credible proposal to provide real autonomy for the Western Sahara".
He said: "The United States hopes Morocco's presentation of its initiative to the United Nations will spur discussion and create an opportunity for Morocco and the Polisario to engage in direct negotiations, without preconditions, to resolve the Western Sahara dispute."
The French foreign ministry said the plan offered a constructive step toward negotiations and the possibility of "a political solution endorsed by all the parties within the framework of the United Nations".