"We have decided to hold the next round of talks on January 14," UN special envoy Ismail Ould Cheikh Ahmed told reporters, adding that the location of the next round had yet to be decided.
A halt to the violence is sorely needed in the Arabian Peninsula's poorest nation, where the UN says fighting since March has killed thousands of people and left around 80 percent of the population needing humanitarian aid.
The talks have been marred from the start by repeated violations of a ceasefire, which in theory began Tuesday and had been scheduled to last a week, but has been breached daily.
Missiles have been fired from rebel-held areas, even slamming down on the Saudi side of the border with deadly consequences, while government forces have seized several areas back from the rebels.
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"Unfortunately there were numerous violations," Ould Cheikh Ahmed said, adding that the UN had called for "a ceasefire which is not time-bound."
These included an agreement "in principle" to release all prisoners, he said, while acknowledging that such an exchange likely would not happen before a sustainable ceasefire had been agreed.
But, he stressed, "I am optimistic about a full prisoner release and that a full prisoner release will take place very soon."
The two sides had also agreed on the need to "lift all forms of blockade and allow safe, rapid and unhindered access for humanitarian supplies to all affected governorates," according to the final statement.
The conflict has escalated dramatically since Saudi-led air strikes against the rebels began in March, with more than 5,800 people killed and more than 27,000 wounded since then, according to UN figures.