The U.N. envoy for Yemen is appealing to the warring parties to finalize a peace deal as soon as possible, saying slow progress has been made in the past two months and it's now time for concessions on the toughest issues.

Ismail Ould Cheikh Ahmed told the U.N. Security Council Tuesday that the parties — Houthi Shiite rebels and allied troops loyal to an ex- president and Yemen's internationally recognized government — responded positively to a proposed roadmap he presented to end the conflict.

But Cheikh Ahmed said by video that they haven't agreed on the timing of steps — including when a national unity government would be created.

The Yemen conflict has killed some 9,000 people since March 2015 and Cheikh Ahmed called the humanitarian situation "alarming."