RIYADH - A humanitarian pause in the war in Yemen will be "useless" because rebels and their allies have shown no readiness to abide by it, a Saudi official said Friday.

The United Nations announced the pause, to take effect from 2059 GMT Friday, to allow aid to reach millions of Yemenis on the brink of famine.

A Saudi-led coalition launched bombing raids in March on Iran-backed Huthi rebels in Yemen to support forces loyal to exiled President Abedrabbo Mansour Hadi. "I believe the coalition has not received... any evidence of commitment of the other party," said the official who asked not to be identified. "We believe that this pause will be useless."

He added that the rebels do not have full control of all of their allied forces.

The coalition in May accused the Huthis of numerous violations of a five-day truce which at that time was proposed by Saudi Arabia.

Among the transgressions it cited were rockets fire from Yemen which landed in Saudi border districts.

"We should not let that happen again," the Saudi official said.

The coalition also accused the rebels of moving missiles towards the Saudi frontier during the last truce.

After halting air strikes for the five days, coalition bombing resumed an hour after the pause ended.

The coalition believes rebels will "abuse" the new pause but, if they make commitments to respect it, "definitely the coalition will" do the same, the official said.

UN spokesman Stephane Dujarric said in New York that Secretary-General Ban Ki-moon has received assurances from Hadi and the Huthi rebels that they will respect the pause.

It is to last for six days until the end of the Muslim fasting month of Ramadan.

The UN says violence has been escalating and humanitarian access decreasing in a war zone where more than 3,200 people have died and millions need assistance.

On the Saudi side of the border, at least 44 civilians and troops have been killed in skirmishes and shelling.

Meanwhile, aid agencies scrambled Friday to rush in desperately needed relief supplies to millions of Yemenis threatened with famine amid guarded hopes for a six-day truce to take effect before midnight.

The United Nations on Thursday announced a six-day ceasefire that will begin Friday at 11:59 pm (2059 GMT) and last until the end of the Muslim fasting month of Ramadan on July 17.

But hours before the deadline, warplanes from the Saudi-led coalition pounded positions of Iran-backed rebels, more than three months into their campaign in support of exiled President Abedrabbo Mansour Hadi. World Food Programme spokeswoman Abeer Etefa told AFP that the truce was "our final hope" to reach areas in need of aid.

She added that two ships carrying food and fuel were waiting to dock off the coast of the southern port city of Aden.

The pause was declared after UN Secretary General Ban Ki-Moon received assurances from Hadi and Huthi rebels that it would be respected.

It comes more than a week after the UN declared Yemen a level-3 humanitarian emergency, the highest on its scale, with nearly half the country facing a food crisis. "It is imperative and urgent that humanitarian aid can reach all vulnerable people of Yemen unimpeded and through an unconditional humanitarian pause," UN spokesman Stephane Dujarric said.

UN aid agencies are ready to scale up operations during the pause, although the response to an appeal for $1.6 billion has been meagre, with just 13 percent of that amount received so far.

More than 21.1 million people -- over 80 percent of Yemen's population -- are in need of aid, with 13 million facing food shortages. The UN says the conflict has killed more than 3,200 people, around half of them civilians, since late March.

This will be the second ceasefire since the Saudi-led coalition launched an air campaign against the Iran-backed northern rebels and their allied troops loyal to former president Ali Abdullah Saleh in March. A five-day truce in May allowed aid to reach civilians caught in the fighting, but UN efforts to prolong the ceasefire failed.

"We hope that this truce will pave the way for ending the Saudi aggression," said Mohammed Ali al-Huthi, head of the rebels' Supreme Revolutionary Committee.

The Huthis overran Sanaa unopposed in September and have since expanded their control over several regions, aided by troops loyal to Saleh.

They pushed Hadi into exile when they advanced in March on the southern city of Aden, where he took refuge after escaping house arrest in Sanaa.

The Minister of Human Rights in Hadi's exiled government, Ezzedine al-Asbahi, cast doubt over the rebels' commitment to the truce.

"They exercise high-level trickery, even with the international community. Their military movements on the ground do not reflect a good will, or sincere decision to cement a humanitarian truce," he told AFP.

Sanaa resident Mohammed al-Juhayfi said he was already dreading the end of the forthcoming truce. "We do not want a truce of five or ten days, which we will then count by the minute. We want a full solution for the Yemen crisis," he said.

The Saudi-led coalition did not comment on ceasefire.

On Friday, warplanes hit rebel positions north of Sanaa, as well as in the rebel northern stronghold of Saada, witnesses said. Air raids also targeted rebels in the provinces of Marib, Dhamar and Baida.

In Aden, where heavy clashes continued between rebels and southern fighters allied with Hadi, coalition warplanes struck rebel positions in al-Muala district and the northern and western outskirts of the port city, military sources said.

Meanwhile, nine civilians were killed when an air raid mistakenly struck a school housing displaced families in the village of Tibn, in southern Lahj province, a local official told AFP.