A ceasefire to halt nine months of war in Yemen will now begin on Tuesday morning instead of midnight as previously announced, coinciding with the start of UN-backed peace talks in Switzerland.
The delay came after Saudi and Emirati authorities said on Monday that two senior coalition officers were killed near the city of Taiz in Yemen's southwest.
Saudi Colonel Abdullah al-Sahyan and Emirati officer Sultan al-Ketbi died at dawn "while they were carrying out their duties in supervising operations to liberate Taiz", the official Saudi Press Agency news agency said.
The Emirati state news agency WAM separately confirmed Ketbi's death.
Media controlled by the Houthi rebels said the two were killed in a rocket attack on the Red Sea coast.
The Saudi-led coalition supporting Yemen's government said the truce will now begin at 09:00 GMT (12pm local time) following a request from President Abd-Rabbu Mansour Hadi.
It warned, however, that it "reserves the right to respond in case of any violation" by the rebels, said a statement carried by the SPA state news agency.
"The ceasefire [will last] for a period of seven days starting from the 15th to the 21st of December in conjunction with the launch of consultations, and will be renewed automatically in the event of the commitment of the other party," the statement said.
READ MORE: Yemen's warring sides agree to ceasefire before talks
The Houthi attack on Monday was a clear blow to the Saudi-led alliance.
Sahyan on Saturday had met Hadi who awarded him with a medal of courage, according to Yemen's official sabanews.net website.
He was identified as commander of the Saudi forces in the provisional capital Aden, where Hadi's government is based.
Saudi-led forces backing Hadi launched an offensive in Yemen in March to push back the Houthis.
The fighters - backed by forces loyal to former president Ali Abdullah Saleh - have seized large parts of the country, including the capital, Sanaa.
The Houthis and Saleh's former political party, the General People's Congress, are sending representatives to Switzerland on Tuesday for talks with Yemen's internationally recognised government under Hadi.
A seven-day renewable ceasefire was scheduled to come into effect on Monday to coincide with the talks. Two previous attempts at ceasefires, in May and July, were followed by accusations of breaches by both sides.
The United Nations says more than 5,800 people have been killed in Yemen, about half of them civilians, since March.
It has also pushed Yemen to the brink of famine.
In early September, a rebel missile strike on a coalition base in Yemen's eastern Marib province killed 67 coalition soldiers, most of them Emiratis.
So far at least 80 people, mostly soldiers and border guards, have been killed in Saudi Arabia because of the Yemen conflict.
The UAE says it has lost almost 70 soldiers so far.
Several Bahraini troops and one Qatari soldier have also been killed as part of the coalition operations.
Source: Al Jazeera