A second round of talks on the disputed Western Sahara region ended Friday with the sides agreeing to meet again, but with the UN acknowledging many positions remained far apart.
Morocco and the Polisario Front liberation movement appeared to have come no closer on the thorny issue of an independence referendum to decide Western Sahara's fate.
The Polisario has demanded a vote -- a proposal categorically rejected by Rabat.
"This is not and will not be easy," United Nations envoy and former German president Horst Kohler told reporters in Geneva.
"There is still a lot of work ahead," he said.
"Nobody should expect a quick outcome, because many positions are still fundamentally diverging."
Foreign ministers from Morocco, Algeria and Mauritania along with the Polisario's chief negotiator spent the past two days meeting in a secret location "near Geneva".
Kohler read a joint communique hailing the delegations for engaging in "courteously and openly in an atmosphere of mutual respect."
The talks focused on finding "a mutually acceptable political solution ... that is realistic, practicable, enduring, based on compromise, just, lasting, (and) which will provide for the self-determination of the people of Western Sahara," the communique said.
The parties had agreed to "continue the discussion in order to identify elements of convergence," it added.
Moroccan Foreign Minister Nasser Bourita told journalists the sides agreed to meet before the summer.
The international community has long advocated that a referendum be held to decide the status of Western Sahara, a former Spanish colony on the western edge of the vast eponymous desert, stretching around 1,000 kilometres (600 miles) along the Atlantic coastline, a prime fishing region.
The Polisario fought a war with Morocco from 1975 to 1991, when a ceasefire deal was agreed and a UN peace mission was deployed to monitor the truce.
Morocco, which annexed the territory after Spain withdrew in 1975, considers Western Sahara an integral part of the kingdom and has offered autonomy instead of an independence referendum.
This week's talks followed an unproductive round at the UN in Geneva last December after six years of stalemate.
The positions did not appear to have gotten much closer on Friday.
Bourita reiterated his country would discuss "autonomy", but that under no circumstances would it "accept a referendum where one of the options is independence."
Polisario delegation head Khatri Addouh meanwhile insisted the Sahrawi people should be allowed to freely express themselves on how the territory should be run.
"Besides a free referendum, organised by the UN and guaranteed by the UN, we do not see how such an expression can take place," he told reporters.
The new round of talks comes as the mandate of the UN peacekeeping mission that has helped guarantee a ceasefire in Western Sahara since 1991 is about to end next month.
The United States has warned it may allow MINURSO's presence in Western Sahara to lapse, or it could agree to prolong its mandate by another six months.
Other Security Council members are pushing for a longer engagement, including France which wants the mandate extended for a year.