Addressing the Security Council, Martin Griffiths said a possible sharp escalation from the missile attacks on Saudi Arabia and intensified fighting could "in a stroke, take peace off the table."

"My plan is to put to the council within the next two months a framework for negotiations," Griffiths said in his first council report since taking over as special envoy in February.

The Saudi-led coalition battling Yemen's Huthi rebels on Monday warned it was ready to inflict a "painful" response if new attacks are carried out against Saudi Arabia.

Riyadh said last week it had shot down two Iran-supplied drones in the south of the kingdom and intercepted ballistic missiles fired from rebel-held parts of Yemen, the latest in a series of similar incidents.

Griffiths cited the increased missile launches, intensified military operations in northwest Saada governorate, ongoing air strikes and movements of forces in the Hodeidah region as worrisome developments.

"Our concern is that any of these developments may, in a stroke, take peace off the table. I am convinced that there is a real danger of this," said the envoy.

Griffiths briefed the council after traveling to the region for talks in Riyadh, Sanaa and other key capitals on prospects for re-launching peace talks which he insisted to the council "can be done."

The previous UN envoy, Ismail Ould Cheikh Ahmed, had fallen out with the Huthis who refused to welcome him to Sanaa.

- Calling out Iran -

UN diplomats say Iran, which has backed the Huthis, has signaled that it is ready to work for a settlement in Yemen, which the United Nations describes as the world's worst humanitarian crisis.

US Ambassador Nikki Haley thanked Griffiths, a British national, for taking on "one of the world's most difficult diplomatic assignments" but stressed the new peace effort must address Iran's military support to the Huthis.

While backing the new peace efforts, the Security Council cannot be "afraid to call out the Huthis and their Iranian patrons by name in future resolutions," said Haley.

Russia in February vetoed a British-drafted resolution strongly supported by the United States that would have put pressure on Iran over its failure to block supplies of missiles to the Huthi rebels.

Iran has repeatedly denied arming the Huthis in Yemen, despite claims by the United States and Saudi Arabia that the evidence of an arms connection is irrefutable.

Russia's Ambassador Vassily Nebenzia backed UN efforts for peace but warned, in an implicit swipe at the United States, that "this can be done only if there is a focus on Yemen itself, rather than attempts to introduce geopolitical calculations in this conflict."

More than 9,200 people have been killed since the Saudi-led alliance joined the Yemen war, according to the World Health Organization.

An overwhelming 75 percent of the population -- 22 million people -- is in need of aid, seven million of whom are at risk of famine, while one million Yemenis have been ill from cholera.

With the return of the rainy season, Yemen once again risks another major outbreak of cholera, UN aid chief Mark Lowcock told the council.