Women walk on a bridge in the old quarter of Yemen’s capital Sanaa April 9, 2016.

A ceasefire between Yemen’s warring parties which began at midnight local time (2100 GMT) on Sunday appears to largely be holding despite reports of clashes, the UN spokesman said.

Shortly after the truce began, clashes were reported in the city of Taiz, which has partly been besieged by the Iranian-backed Houthis, despite pledges by pro-government forces and militias to honor the truce.

However UN spokesman Stephane Dujarric confirmed that “the cessation of hostilities seems to be largely holding,” – yet noted that there were “some pockets of violence.”

The Houthi militias, along with allied troops loyal to ex-president Ali Abdullah Saleh, have sent the United Nations a letter committing to “cease land, sea and air military operations” throughout Yemen, according to a communique carried by the rebel-run Saba news agency.

The chief of staff of forces loyal to President Abedrabbo Mansour Hadi confirmed “the ceasefire has taken effect”.

General Mohamed Ali al-Makdashi told reporters that “we are going to respect it… unless the Houthi rebels violate it”.

A Saudi-led coalition has for more than a year been supporting the Hadi forces against the Houthis who seized much of Yemen including the capital Sanaa. The coalition also said it would respect the truce.

Yemen’s foreign minister expressed alarm after reported breaches minutes after a ceasefire went into effect at 2100 GMT on Sunday in the country, just a week before the upcoming UN-sponsored peace talks in Kuwait.

“Until now we do not know if the violations were intentional but we will evaluate in the next few hours to see if they were,” Yemeni Foreign Minister Abdulmalik Al-Mekhlafi told Al Arabiya News Channel.

“If these violations prove to be intentional, we will retaliate,” he warned.

Sources told Al Arabiya News Channel that Iran-backed Houthi militias breached the ceasefire with reports of heavy clashes taking place in the eastern part of Yemen’s Taiz.

Mohammad al-Kamari, a resident in Taiz told Al Arabiya English in a phone interview that “Houthis violated the ceasefire and began attacking [pro-government] resistance forces in Taiz,”

Shelling could be heard in the background during the phone interview with Kamari, who said he first heard the gunfire at 2200 GMT.

Mohammed al-Rumim, a Yemeni activist in Taiz, told Al Arabiya that shelling fell close to a nearby hospital, frightening patients.

“I know of one person who has died and there are many injured. People are very angry by the acts of Houthi and Saleh militia,” Rumim said, refereeing to loyalist of former president Ali Abdullah Saleh who was ousted in 2011.

The UN’s special envoy for Yemen, Ismail Ould Cheikh Ahmed, urged all parties to ensure that the cessation of hostilities are respected, in a message posted on Facebook.

“Both sides have committed to adhere to the terms and conditions for the cessation of hostilities which I presented,” said the envoy. “I ask all the parties and the international community to remain steadfast in support for this cessation of hostilities to be a first step in Yemen’s return to peace. This is critical, urgent and much needed. Yemen cannot afford the loss of more lives.”

But the Houthi rebels vowed to respect the truce that began, joining other combatants in supporting the ceasefire.

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