A hard-won truce in the battleground Yemeni city of Hodeida will collapse if rebel violations persist and the United Nations does not intervene, the Saudi-led coalition said on Wednesday.
UN observers are due in Yemen to head up monitoring teams made up of government and rebel representatives tasked with overseeing the implementation of the UN-brokered ceasefire that took effect on Tuesday.
The UN Chair of the Redeployment Coordination Committee, will convene its first meeting by videoconference from New York on Wednesday before heading to Yemen "later this week", UN spokesman Stephane Dujarri said.
Hodeida residents reached by telephone said there was complete calm in the Red Sea port city on Wednesday morning following intermittent gunfire during the night.
But the Saudi-led coalition, which has been fighting alongside the government since March 2015, complained of repeated rebel breaches since the truce went into effect.
"A total of 21 violations since ceasefire commencement have come to our notice," a coalition source told AFP on condition of anonymity.
"If the UN continues to drag the chain and take too long to get into the (military) theatre, they will lose the opportunity altogether... and the agreement will turn a dead duck," the source said in English.
"We will continue to give them the benefit of the doubt and show restraint but early indicators are not promising."
The rebels, in turn, accused pro-government forces of violating the truce agreed at landmark talks in Sweden earlier this month.
The rebel-run Saba news agency said loyalist forces targeted several areas of the city and its surrounding province overnight.
The observers of the Redeployment Coordination Committee are due to oversee the withdrawal of the warring parties from the city, including a rebel pullout from the city's docks that are the point of entry for 80 percent of Yemeni imports and nearly all UN-supervised humanitarian aid.
The committee chair is expected to report to the UN Security Council on a weekly basis as part of a major diplomatic push to end the four year-old conflict that is seen as the best chance yet for peace.
- 'Wicked war' -
The war between the the Huthi Shiite rebels and troops loyal to President Abedrabbo Mansour Hadi escalated in 2015, when he fled into Saudi exile and the Saudi-led military coalition intervened.
Since then, the war has killed some 10,000 people, according to the World Health Organization, although human rights groups say the real death toll could be five times as high.
The conflict has also pushed 14 million people to the brink of famine in what the United Nations describes as the world's worst humanitarian crisis.
The warring sides have both welcomed the truce.
In addition to the UN-supervised withdrawal of fighters from Hodeida, the International Committee of the Red Cross is due to oversee a promised exchange of prisoners involving some 15,000 detainees.
A "mutual understanding" was also reached to facilitate aid deliveries to Yemen's third city Taiz -- under the control of loyalists but besieged by rebels.
The two sides have agreed to meet again in late January for more talks to define the framework for negotiations on a comprehensive peace settlement.
Hodeida residents said on Tuesday they hoped the truce would hold and lead to lasting peace in the war-ravage Arabian Peninsula country.
"We hope that this ceasefire agreement holds and for this war to end because the people of Yemen has had enough of this wicked war," Amine Awad told AFP.