The Saudi-led coalition fighting Yemen's Houthi group had said it would stop military operations from Wednesday after the Iran-aligned movement this week declared a three-day cessation of cross-border attacks and ground offensives in Yemen.

As part of efforts to end the seven-year war that has killed tens of thousands and pushed millions into hunger, the unilateral initiatives followed a UN call for a truce during the Muslim holy month of Ramadan that starts this week.

The spokesman for UN Secretary-General Antonio Guterres voiced hope the cessation would create momentum to end violence, advance stalled political negotiations and alleviate a dire humanitarian crisis by easing restrictions on imports such as fuel.

"We urge the parties to use this opportunity to engage constructively and without preconditions with Special Envoy (Hans) Grundberg and his mediation efforts," the spokesman said in a statement.

Two sources familiar with the matter had said the United Nations had drafted a proposal for a temporary truce during Ramadan in exchange for allowing fuel ships to dock at Houthi-held Hodeidah port and a small number of commercial flights to operate from Sanaa airport.

The status of the proposal was unclear following the individual announcements by the Houthis and the coalition, which controls Yemen's seas and air space. The Houthis refused to attend the week-long Yemeni talks in Riyadh, saying they should have been held in a neutral country.

The UN and the United States have since last year been trying to secure a permanent truce but the warring sides refused compromise. The Houthis want the coalition to lift its blockade while the alliance wants a simultaneous deal.

Riyadh has struggled to exit the conflict that is largely seen in the region as a proxy war between Saudi Arabia and Iran.

The Houthis, who ousted Yemen's Saudi-backed government from the capital, Sanaa, in late 2014, say they are fighting a corrupt system and foreign aggression.