The UN’s Libya mission and world powers on Tuesday urged the country’s warring parties to engage in peace efforts, as doubts hung over talks set to start the next day in Geneva.

The negotiations are supposed to gather delegates from a Tripoli-based unity government and representatives of an eastern-based parliament backed by military commander Khalifa Haftar, who is leading a months-long offensive to seize the capital.

Both sides had said Monday they would not take part in the negotiations in Switzerland, citing different reasons.