UNITED NATIONS (AP) — The U.N. Security Council called Thursday for an immediate end to a “significant” escalation in fighting in Yemen between Houthi Shiite rebels and the Saudi-led military coalition supporting the government.

Member nations on the U.N.’s most powerful body “underlined their disappointment” at the return to violence in a statement, saying it “threatens to undermine progress made during the recent period of de-escalation in Yemen.”

The council expressed hope “that a renewed de-escalation would create space for the Yemeni parties to move towards comprehensive and inclusive U.N.-led negotiations urgently, on the security and political arrangements necessary to end the conflict and move towards a peaceful transition.”

The council statement followed a briefing Tuesday by the U.N. special envoy for Yemen, Martin Griffiths. He urged a halt to the recent “alarming military escalation” in fighting “before it is too late.”

Less than two weeks ago, Griffiths had reported to the council on a major reduction in military operations and other initiatives. He expressed hope then that this would lead to talks between the government and Iranian-backed Houthis on ending the five-year conflict in the Arab world’s poorest nation.

The U.S.-backed Arab coalition battling to restore Yemen’s internationally recognized government stepped up airstrikes in recent days on rebel targets northeast of the capital, Sanaa, while the Houthis shelled government-held areas.