The U.N. envoy to Libya is cautiously optimistic that candidates to run a government uniting all the conflict-torn country's political factions could be named this week.

Bernardino Leon said Monday in Brussels that "there is a chance that we can make progress and have the first names for a unity government this week."

However, he warned against expectations that are "too high, bearing in mind how difficult the situation is on the ground."

Leon spoke during a break in talks involving Libya's mayors aimed at setting up zones for providing humanitarian aid and basic services as well as sending a message of peace.

Libya has two parliaments and two governments, along with rival militaries and militias.

The power struggle and fierce fighting have plunged the country into chaos and paved the way for the Islamic State group's expansion.

Leon praised the mayors for meeting despite fighting in some of their cities over the weekend and even though the talks in Brussels could bring them face to face with officials from enemy factions.

"These mayors are courageous," he told reporters. "We have cities that have been bombed in recent days, have suffered terrorist attacks in recent days."

"The war is making people pay a heavy price. There are cities that have problems with medicines, with food," he said.

The European Union's top diplomat, Federica Mogherini, said that the EU stands ready to help Libya, but only once a unity government has been formed.

Libya is the main departure point from Africa for migrants fleeing poverty and war in search of better lives in Europe, and EU officials fear that extremists might also make the crossing.

But the EU is reluctant to send resources or personnel before the fighting stops.