SANAA: At least 24 civilians were killed in an air raid Sunday on a market in northern Yemen, a medical official and witnesses said, blaming the Arab coalition battling Yemeni rebels. Most of the casualties worked in the Mashnaq market in the rebel-controlled Saada province on the Saudi border, an official at a nearby hospital told AFP on the condition of anonymity.

Witnesses said the market was a center for trafficking in qat, a leafy stimulant plant that is widely used in Yemen but illegal in Saudi Arabia.

One of the witnesses said some of the casualties had “just returned from a trip across the border.”

The Arab military coalition has been carrying out airstrikes in Yemen for more than two years against areas controlled by the Shiite Houthi rebels.

Saada itself has come under heavy bombing since 2015, when the coalition intervened to support the government of Abed Rabbou Mansour Hadi in its fight against the Iran-backed Houthis.

The coalition claimed responsibility for a deadly attack on the rebel-held capital Sanaa in October 2016 which targeted a gathering of mourners at a funeral ceremony, killing more than 140 people.

The Houthis have also accused the coalition of a raid last month that killed 23 civilians, including women and children, in the southwestern city of Taiz.

The coalition – which accused the rebels of using civilians as “human shields” – has not claimed responsibility for that attack.

The rebels, who control a string of strategic ports along the Red Sea coastline and the northern highlands that border Saudi Arabia, have sporadically launched rocket attacks across the border.

In late January, the Houthis attacked a Saudi warship in the Red Sea, killing two sailors.

More than 8,000 people have been killed in the past two years and tens of thousands wounded in the war in Yemen, according to the World Health Organization.

The U.N. has called Yemen the “largest humanitarian crisis in the world” and warns that 17 million people, or two-thirds of the population, face a serious threat of famine this year. More than 900 people have died of cholera in recent weeks in the second outbreak of the deadly infection in less than a year in Yemen, the poorest country in the Arab world long before the war.

Saturday, Yemen’s government said it agreed to a two-point plan advanced by the United Nations to ease suffering in the country’s civil war, but the Houthi movement remained skeptical.

Thursday, the U.N. Security Council urged the warring parties to agree on a U.N.-brokered plan to keep the Houthi-held port of Hudaida out of the fighting and to resume government salary payments.

The U.N. has proposed that Hudaida, a vital aid delivery point on the Red Sea where some 80 percent of Yemen’s food imports arrive, should be turned over to a neutral party. The U.N. Security Council warned the coalition against any attempt to extend the war to the port.

Yemeni Foreign Minister Abdulmalek al-Mikhlafi said in a tweet his government renewed its acceptance of the proposals first made by U.N. Yemen envoy Ismail Ould Cheikh Ahmed in May.

But a spokesperson for the Houthis said the Security Council through its statements was encouraging the Arab alliance to resume its strikes and that they reserved the right to respond to any aggression.

“We reaffirm that the army and local committees have all the right and legality to respond to the alliance,” a statement by spokesperson Mohammed Abdelsalam said.

The coalition has accused the Houthis of using Hudaida to smuggle in weapons and ammunition and has called for U.N. monitors to be posted there. The Houthi movement denies the allegations.

Many thousands of Yemeni state workers are also facing destitution as their salaries have gone largely unpaid for several months after the internationally recognized government shifted Yemen’s central bank to Aden from the capital Sanaa.

U.N. envoy Cheikh Ahmed had told the Security Council on May 30 that he had proposed a deal to avoid military clashes in Hudaida to be negotiated in parallel with an agreement to resume civil service salary payments nationally.

However, he noted the Houthis and the allied General People’s Congress, the party of former President Ali Abdullah Saleh, would not meet with him.